Most articles with this title are about mindset. This one is about paperwork, because in the UK the difference between a side income that compounds and one that quietly evaporates is almost never talent. It is whether you registered on time, chose the right legal structure, understood which threshold you were about to cross, and filed before the automatic penalties started.
Britain is genuinely one of the easier places in the world to start earning on your own account. You can be a legally trading sole trader within an afternoon and at zero cost. You can incorporate a limited company for £100 and be registered inside 24 hours. What Britain is not is forgiving about deadlines. HMRC and Companies House both run automatic, unattended penalty systems that do not care whether you made any money. A dormant company that files its accounts seven months late owes £1,500 to Companies House on turnover of nothing.
This guide covers the specific machinery: sole trader versus limited company, the trading allowance, Self Assessment registration and its penalties, National Insurance as it now stands, VAT, Making Tax Digital, IR35, and the Companies House regime. Every figure below comes from a primary source, and the sources are linked at the end so you can check the current position yourself before acting. Tax thresholds change at Budgets. Treat this as a map, not a substitute for reading the source on the day you act.
Before the mechanics, a calibration. Self-employment and small business income in the UK is extremely skewed. A handful of people earn very large sums; the median is modest; a large tail earns very little or loses money. Any "average earnings" figure published by a platform, a marketplace or a franchise is close to meaningless because a right-skewed distribution has an average dragged upwards by a tiny number of outliers. If a company tells you its sellers earn an average of some figure per year, the useful questions are: what is the median, what share earned nothing, and over what period were people counted. Almost nobody publishes those.
So this page does not contain income projections, case studies or success stories. There are none here that could be verified to a named, citable source, and inventing them would be worse than useless.
What the page does contain is the set of rules that determine your effective tax rate, your compliance cost and your exposure to penalties. Those are knowable, they are the same for everyone, and getting them right is worth a large and predictable percentage of whatever you do end up earning. That is the part of "getting rich" that is actually under your control on day one.
There are two realistic structures for a person starting out alone: sole trader, or a private company limited by shares. Partnerships and LLPs matter if you have a co-owner, but the one-person case is the common one.
The usual advice is "incorporate once profits pass some threshold", and a specific number is often quoted. Be sceptical of any single crossover figure, because the crossover moved in April 2026 and it depends on facts specific to you.
Here is what actually drives it, using current published rates.
A sole trader in England, Wales or Northern Ireland pays Income Tax at 20% on taxable income from £12,571 to £50,270, 40% from £50,271 to £125,140, and 45% above that, with the Personal Allowance of £12,570 tapering away by £1 for every £2 of adjusted net income over £100,000. On top of that, Class 4 National Insurance runs at 6% on profits between £12,570 and £50,270 and 2% above £50,270. So a sole trader's marginal rate on profit in the basic rate band is 26%, and in the higher rate band 42%.
Scotland is different, and this catches people out. For 2026 to 2027 Scottish taxpayers face a starter rate of 19% from £12,571 to £16,537, basic 20% to £29,526, intermediate 21% to £43,662, higher 42% to £75,000, advanced 45% to £125,140 and top rate 48% above that. National Insurance is not devolved, so Class 4 is the same everywhere. The practical effect is that a Scottish sole trader hits a 42% income tax rate at £43,663, roughly £6,600 earlier than someone in England.
A company pays Corporation Tax at 19% on profits up to £50,000, 25% on profits over £250,000, with Marginal Relief in between. The arithmetic of that relief is worth internalising: tax on £50,000 of profit is £9,500, tax on £250,000 is £62,500, so the £200,000 of profit between the two limits is effectively taxed at 26.5%. Both limits are divided by the number of associated companies and reduced pro rata for accounting periods shorter than 12 months. If you own three companies, your small profits limit is £16,667 each, not £50,000 each.
Then you have to get the money out. For 2026 to 2027 the dividend allowance is £500, and dividend tax rates are 10.75% at basic rate, 35.75% at higher rate and 39.35% at additional rate. Those basic and higher rates are two percentage points higher than they were before April 2026, which is precisely why the old crossover advice is stale. A basic-rate owner-director paying 19% Corporation Tax and then 10.75% dividend tax on the remainder faces a combined rate of about 27.7% on that profit, against a sole trader's 26%. At the basic rate the company is now marginally worse on tax alone, before you add the cost of running it.
The picture changes higher up. In the higher-rate band, a sole trader pays 42% at the margin. A company paying 19% Corporation Tax and then 35.75% dividend tax on the balance gives a combined rate of about 48%, which is worse. But that comparison assumes you take everything out as dividends in the same year. The real advantage of a company is not the headline rate; it is control over timing and over the form of extraction. Profit retained in the company is taxed once at 19% or 25% and can be left there, invested, or paid out in a later year when your personal rate is lower. Employer pension contributions made by the company are a deductible business expense and skip the dividend layer entirely. A modest salary can be paid to use up the Personal Allowance.
The costs of running a company are not trivial and are usually understated. Incorporation is £100 online. The confirmation statement is £50 a year. Accounts must be prepared to a statutory format and filed. Most one-person companies pay an accountant somewhere in the range of roughly £600 to £1,500 a year for annual accounts, the Corporation Tax return, a simple payroll and Self Assessment. That range is an estimate based on how the market for small-company compliance is typically priced; it is not a sourced figure and you should get two or three actual quotes rather than trusting it. Add software, and add your own time.
One structural point that gets missed: you cannot casually take money out of a company. Money in the company bank account is not yours. Taking it without declaring it as salary or a properly documented dividend creates a director's loan, which carries its own tax consequences, and paying dividends out of a company that does not have sufficient distributable profits is unlawful. This is the single most common way a first-time director creates an expensive problem.
HMRC gives individuals a trading allowance of "up to £1,000 a year" of tax-free gross trading income. It covers self-employment, casual services such as babysitting or gardening, and hiring out personal equipment. It does not apply to trading income from a partnership.
Four things about it are consistently misunderstood.
A separate trap: if you have other untaxed income that is not trading income, different rules apply. Between £1,000 and £2,500 you are told to contact HMRC; above £2,500 you register for Self Assessment. Rental income, in particular, has its own £1,000 property allowance and its own logic.
The registration deadline is 5 October following the end of the tax year in which you needed to start filing. GOV.UK states it plainly: you must tell HMRC by 5 October 2026 if you need to complete a return for the previous tax year, meaning the year that ran from 6 April 2025 to 5 April 2026. Miss it and, in GOV.UK's words, "you could get a penalty".
That penalty is a failure to notify penalty, and it is not a flat fee. It is calculated as a percentage of the tax you failed to declare, and the percentage depends on your behaviour and on whether you came forward voluntarily. HMRC's published bands are:
Note the 0% floor in the first row. If you realise you were late, tell HMRC yourself before they contact you, and do it within 12 months of the tax falling due, the penalty can be reduced to nothing. Once HMRC prompts you, the floor rises. That single fact is worth more than most tax tips: unprompted beats prompted, every time, by a wide margin.
Once registered you get a Unique Taxpayer Reference. Then the annual deadlines apply. For the 2025 to 2026 tax year: paper returns by 11:59pm on 31 October 2026; online returns and payment by 11:59pm on 31 January 2027; and 30 December 2026 if you want a balance under the coding-out limit collected through your PAYE tax code instead of paid as a lump sum.
Late payment is charged separately: 5% of the tax unpaid at 30 days, again at six months, and again at twelve months. Interest runs on top. HMRC's late payment interest rate has been 7.75% since 9 January 2026, set at Bank of England base rate plus 4%. That plus-4% margin has applied since 6 April 2025; before then it was base plus 2.5%. Repayment interest, which is what HMRC pays you when it owes you money, is 2.75%, set at base rate minus 1% with a floor of 0.5%. The five percentage point gap between what HMRC charges and what it pays is deliberate and is not going to be argued away.
This is the mechanism that ambushes more first-time self-employed people than any other, and it is not a penalty or a trap. It is simply badly explained.
Payments on account are advance payments towards your next tax bill. Each is half of the tax you owed last year. They are due by midnight on 31 January and 31 July. You are exempt if your last Self Assessment bill was under £1,000, or if you paid more than 80% of your tax at source, for example through a PAYE tax code.
The consequence in your first profitable year is that on 31 January you pay the whole of last year's tax plus half of it again as the first payment on account. If you owed £6,000, you write a cheque for £9,000. Six months later you pay another £3,000. If your income has grown, the following January brings a balancing payment plus a larger first instalment.
Two practical responses. First, from the day you start trading, move a fixed percentage of every payment received into a separate account and do not touch it. For a basic-rate sole trader, 26% is your marginal rate on profit, so setting aside 30% of profit is a reasonable buffer, and 35% to 40% if you are anywhere near the higher rate band. That is a rule of thumb, not a calculation of your liability. Second, if your income has genuinely fallen, you can apply to reduce your payments on account, but if you reduce them below what turns out to be due, HMRC charges interest on the shortfall. Reduce cautiously.
National Insurance for the self-employed changed materially in recent years and a lot of published advice has not caught up.
The voluntary decision is where the money is. Voluntary Class 2 at £3.65 a week is by far the cheapest way to buy a qualifying year on your National Insurance record. The alternative for most people who are not self-employed is Class 3 at £18.40 a week, roughly £957 a year. You need 35 qualifying years for the full new State Pension, which is currently £241.30 a week, and at least 10 qualifying years to get anything at all.
So if you have a low-profit self-employed year, paying £189.80 to secure a qualifying year is usually a straightforwardly good deal, and paying £957 later to fill the same gap is a much worse one. To pay voluntary Class 2 you must be registered for Self Assessment, which is one of the four reasons GOV.UK gives for registering even when you are under the trading allowance. Check your National Insurance record before you decide, because if you already have 35 years, buying more adds nothing.
One thing Class 2 and Class 4 do not buy you: they do not give access to the full range of contributory benefits that employees get. Statutory Sick Pay does not apply to the self-employed. Budget for your own income protection or accept the risk explicitly.
VAT: The £90,000 Threshold, the Two Tests, and What Voluntary Registration Really Does
The VAT registration threshold is £90,000 of taxable turnover. There are two separate tests and you must monitor both.
The backward look. You must register if your total taxable turnover for the last 12 months goes over £90,000. This is a rolling 12 months, not your accounting year and not the tax year. Every month you should be adding up the previous twelve. When the total crosses £90,000, you have 30 days from the end of that month to register, and your effective date of registration is the first day of the second month after you went over.
The forward look. You must register if you expect your taxable turnover to go over £90,000 in the next 30 days alone. This one is faster and less forgiving: you must register by the end of that 30-day period, and your effective date is the date you realised you would exceed the threshold, not the date you actually did. Sign a single contract worth more than £90,000 deliverable within 30 days and you are registered from the day you knew about it.
Deregistration works at a lower figure. If your taxable turnover falls below £88,000 you can ask HMRC to cancel your registration. The £2,000 gap between registration and deregistration exists to stop businesses flipping in and out around the threshold.
What voluntary registration actually does. You can register below £90,000. Whether you should depends almost entirely on who your customers are.
If you sell to VAT-registered businesses, VAT is close to invisible to them. They pay your VAT and reclaim it. Registering lets you reclaim VAT on your own purchases, which is real money, and it removes the awkward moment when crossing the threshold forces you to either raise prices by 20% or absorb the hit. For a B2B consultant with meaningful software, equipment and subcontractor costs, voluntary registration is often worth doing early.
If you sell to consumers, VAT is a straight 20% problem. Your customer cannot reclaim it. You either raise your price by 20% and become less competitive, or you keep your price and hand a sixth of your revenue to HMRC. This is why a large number of UK consumer-facing microbusinesses deliberately manage turnover to stay under £90,000, which is economically daft but individually rational. If you are in this position, model the cliff before you get near it: at £90,000 of consumer turnover, becoming VAT registered without raising prices costs you £15,000 in output VAT, minus whatever input VAT you can reclaim.
Registration also brings obligations. You must charge VAT correctly, issue compliant invoices, keep digital records, and file VAT returns. VAT has been within Making Tax Digital for some time, so registration means software.
The Flat Rate Scheme and the Limited Cost Business Trap
The VAT Flat Rate Scheme lets you pay a fixed percentage of your gross turnover to HMRC and keep the difference between that and the VAT you charged. You cannot reclaim VAT on purchases, except on capital assets costing more than £2,000. You can join if your VAT taxable turnover is £150,000 or less excluding VAT.
Published sector rates include 14.5% for computer and IT consultancy or data processing, 14% for management consultancy, and 12% for business services not listed elsewhere. There is a 1% discount in your first year as a VAT-registered business.
The thing that gutted this scheme for service businesses is the limited cost business rule. If your goods cost less than 2% of your turnover, or less than £1,000 a year, you are a limited cost business and your rate is 16.5% regardless of sector. Note the word goods. Software subscriptions, accountancy, rent, phone bills and subcontractors are services, not goods, and do not count towards the 2% test.
Work through what 16.5% means. On £100 net plus £20 VAT, your gross is £120. At 16.5% you pay HMRC £19.80 and keep 20p, while being unable to reclaim any input VAT. For a consultant with a laptop and a software stack, the Flat Rate Scheme at 16.5% is worse than standard VAT accounting, often substantially. Do not join it because someone told you in 2015 that it was free money. Run your own numbers against your actual input VAT.
Making Tax Digital for Income Tax: You Are Already Inside the Timeline
Making Tax Digital for Income Tax is the largest change to self-employed compliance in a generation, and the first cohort is already in it.
The thresholds and dates, as published by HMRC:
- From 6 April 2026: if your qualifying income was over £50,000 in the 2024 to 2025 tax year, you should already have started using Making Tax Digital for Income Tax.
- From 6 April 2027: if your qualifying income was over £30,000 in the 2025 to 2026 tax year.
- From 6 April 2028: if your qualifying income was over £20,000 in the 2026 to 2027 tax year.
Two details do the damage. First, qualifying income is gross income from self-employment and property combined, before expenses. Someone with £28,000 of gross self-employment turnover and £14,000 of gross rent has £42,000 of qualifying income and is in scope from April 2027, not out of it. Second, the test looks backwards. Your obligation from April 2028 depends on your income in the tax year that is running right now, 2026 to 2027. If you are near £20,000 of combined gross self-employment and property income this year, assume you are in.
To be in scope you must be registered for Self Assessment as a sole trader or landlord, receive self-employment or property income, and have qualifying income over the relevant threshold. Exemptions exist, including for digital exclusion, and are applied for separately.
What you actually have to do. Keep digital records in compatible software, and send quarterly updates. The standard update periods run to 5 July, 5 October, 5 January and 5 April, with deadlines of 7 August, 7 November, 7 February and 7 May respectively. If your accounting period runs 1 April to 31 March you can elect calendar update periods ending 30 June, 30 September, 31 December and 31 March, with the same 7 August, 7 November, 7 February and 7 May deadlines.
One feature reduces the pain considerably: each quarterly update covers the whole tax year to date, not just the last three months. If you got something wrong in quarter one, you fix it in the quarter two submission rather than filing a correction. Quarterly updates are also not tax calculations. You still file a final tax return by 31 January, and the tax payment dates do not change.
Software. HMRC does not recommend products and maintains a software finder tool. Free products exist "for those with simple tax affairs", but HMRC notes they may carry limits such as a cap on transaction numbers. Check the finder rather than assuming your current spreadsheet or bookkeeping tool is recognised, because the list changes.
If you are below the thresholds you can sign up voluntarily. There is a reasonable argument for doing so a year before you are mandated, so that you learn the software in a year when getting it wrong costs nothing.
The New Penalty Regime That Comes With MTD
Joining Making Tax Digital moves you onto a different penalty system, and it is genuinely different rather than cosmetically so.
Late submission becomes points-based. You get a penalty point for each missed quarterly update or tax return deadline. The threshold is four points. Reach four and you get a £200 penalty, and a further £200 each time you miss another deadline after that. You can only get one point per deadline, even if you run more than one business.
Points below the threshold are removed automatically 24 months after the missed deadline. Once you hit the threshold, automatic removal stops. To clear the points you must submit on time for 12 consecutive months and also submit everything outstanding from the previous 24 months. Getting to four points is therefore not a one-off £200; it puts you in a state that takes a year of clean behaviour to leave.
Late payment becomes percentage-based and front-loaded. For the 2026 to 2027 tax year: nothing if you pay within 15 days; 3% of the tax owed if 16 to 30 days late; and if you are 31 days or more late, 3% charged at day 15 plus a further 3% at day 30, plus interest accruing daily at an annualised 10%. For 2027 to 2028 the two percentage charges rise to 4% each, with the same 10% annualised ongoing charge. There is a first-year easement on the 16 to 30 day charge.
Compare that to the legacy regime, where the first late payment penalty does not bite until 30 days. Under MTD, being a fortnight late now costs money. Set up the payment before the deadline, not on it.
IR35 and Off-Payroll Working: Who Decides, and Why It Matters More When Your Client Is Small
If you contract through your own limited company, IR35 is the single largest determinant of your take-home pay, and the rules are split in a way that is easy to get wrong.
When the client is public sector, or a medium or large private sector organisation, the client determines the worker's employment status for tax. The client must produce a Status Determination Statement giving the reasons for the determination. If the determination is that the engagement is inside the rules, the deemed employer deducts Income Tax and employee National Insurance from the fees paid to your intermediary and pays employer National Insurance to HMRC, plus Apprenticeship Levy where applicable.
When the client is small and outside the public sector, responsibility shifts. In GOV.UK's words, "if a worker provides services to a small client outside the public sector, the worker's intermediary is responsible for deciding the worker's employment status". That means you decide, and you carry the risk if HMRC later disagrees.
People hear "small client, so I decide" and conclude the rules do not apply. They do apply. The older intermediaries legislation still bites; what changes is who does the work of determining status and who bears the liability. Deciding your own status without documenting the reasoning is how a routine enquiry turns into an assessment for several years of PAYE and National Insurance plus interest and penalties.
The size test, and a genuine conflict in the published guidance. A client is medium or large if it meets two or more of three conditions. HMRC's client-facing guidance page, last updated 30 August 2024, states those conditions as turnover of more than £10.2 million, a balance sheet total of more than £5.1 million, and more than 50 employees. HMRC's own Employment Status Manual, however, records that from 6 April 2025 two of the three Companies Act thresholds increased, to turnover of more than £15 million and a balance sheet total of more than £7.5 million, with the employee count unchanged at 50. The manual says the changes apply to financial years beginning on or after 6 April 2025, and that because of how the two-consecutive-year rule and filing deadlines interact, for a normal 12-month financial year the earliest tax year in which the transitional provision affects a client is 2027 to 2028.
The two GOV.UK pages therefore do not agree on their face. Recording that honestly is more useful than picking one: the uplifted figures are the ones in the Companies Act and in HMRC's technical manual, but they phase in through a two-year test, so a client sitting between the old and new thresholds may still be treated as medium or large for now. If your engagement turns on this, get the client's own written statement of its size status and keep it, and read ESM10006a rather than relying on the summary page.
There is also a simplified test for entities that are not companies, LLPs, unregistered companies or overseas companies: they must apply the rules if annual turnover exceeded £10.2 million for the last calendar year, with the rules applying from the start of the tax year following the end of that calendar year.
CEST. HMRC provides the Check Employment Status for Tax tool. Use it, save the output with the date and the answers you gave, and keep it with the contract. HMRC stands behind a CEST result only if the information entered was accurate and the working practices match. The tool does not return an answer in every case. If it returns "unable to determine", that is a signal to get advice rather than to pick the answer you prefer.
One overlooked interaction: an employee whose work falls under the off-payroll rules cannot be counted for Employment Allowance purposes. If you were planning to claim Employment Allowance through your personal service company, check the eligibility rules first.
Running a Limited Company: Duties, Deadlines and What Companies House Actually Costs
Incorporation is cheap and fast. Ongoing compliance is neither difficult nor optional, and the penalties are automatic.
Registration. Registering online costs £100 and companies are usually registered within 24 hours. Registering by post on form IN01 costs £124 and takes 8 to 10 days. There is a same-day incorporation service through software at £156. You will usually be set up for Corporation Tax at the same time as you incorporate.
The current Companies House fee schedule, as published and last updated on 2 July 2026:
- Incorporation: £100 online, £100 via software, £124 on paper.
- Same day incorporation: £156, software only.
- Confirmation statement, covering a 12-month period: £50 online or via software, £110 on paper.
- Change of company name: £20 online or software, £30 on paper; £85 for the same-day service.
- Voluntary strike off: £13 online, £18 on paper.
- Registration of a charge: £14 online or software, £24 on paper.
These figures are materially higher than the ones quoted in most older articles, which is a good reason to check the fee page yourself rather than trusting a blog. Note the confirmation statement fee is per 12-month period, not per filing, so filing an extra confirmation statement mid-year does not cost you again within that period.
Accounts deadlines. A private company must deliver its first accounts within 21 months of the date of incorporation, or 3 months from the accounting reference date, whichever is longer. After that, accounts are due 9 months from the end of the accounting reference period. Delivery means actual receipt at Companies House in the correct format, and deadlines are not extended for weekends or bank holidays.
Late filing penalties at Companies House for a private company:
- Up to 1 month late: £150.
- More than 1 month but not more than 3 months: £375.
- More than 3 months but not more than 6 months: £750.
- More than 6 months: £1,500.
And the rule people forget: the penalty is doubled if accounts are filed late in two successive financial years. These are civil penalties for late delivery. They apply to dormant companies with no income exactly as they apply to trading ones.
HMRC deadlines are different from Companies House deadlines, which is a recurring source of confusion. Corporation Tax must be paid 9 months and 1 day after the end of your accounting period. The Company Tax Return must be filed 12 months after the end of the accounting period. So you pay before you file. That ordering is not a mistake; it is how the regime works, and it means you need a reliable estimate of the liability three months before the return is due.
Company Tax Return late filing penalties:
- 1 day late: £200.
- 3 months late: another £200.
- 6 months late: HMRC estimates your Corporation Tax bill and adds a penalty of 10% of the unpaid tax.
- 12 months late: another 10% of any unpaid tax.
If the return is late three times in a row, the £200 penalties become £1,000 each.
Director duties. GOV.UK sets these out: follow the company's articles of association, keep company records and report changes, prepare annual accounts, file accounts and the Company Tax Return, tell other shareholders if you personally benefit from a transaction the company makes, and pay Corporation Tax. The line that matters most is this one: you remain legally responsible for the company's records, accounts and performance even if you hire an accountant. Failing to meet these responsibilities can result in a fine, prosecution, or disqualification from being a company director.
Identity Verification at Companies House
Since 18 November 2025, identity verification at Companies House is a legal requirement. It applies to directors, equivalent roles such as members, general partners and managing officers, directors of overseas companies, people with significant control, and authorised corporate service providers.
Verification through GOV.UK One Login is free. Using an Authorised Corporate Service Provider instead may cost you, depending on the provider.
The consequences of not verifying are not trivial. Companies House lists prosecution and court fines, financial penalties, and an annotation on the public register. Unverified individuals cannot be appointed as new directors, register new companies, or act as authorised agents. A director who continues to act without verification commits an offence, and so do the company and the other directors.
In practice this means that before you incorporate, each director needs their own personal code from GOV.UK One Login. Build that into your timeline: the 24-hour incorporation turnaround assumes verification is already done.
Getting Money Out of a Company Without Creating a Problem
Three routes, with different tax treatment.
Salary. Deductible against Corporation Tax, subject to Income Tax and Class 1 National Insurance through PAYE. Employee Class 1 is 8% between the primary threshold of £242 a week and the upper earnings limit of £967 a week, then 2%. Employer Class 1 is 15% above a secondary threshold of £96 a week. That £96 secondary threshold is low, which means employer National Insurance starts biting on very modest salaries.
Employment Allowance can offset up to £10,500 of employer Class 1 National Insurance for eligible employers, but there is a specific carve-out that catches personal service companies: if your company has only one director, that director must not be the only employee liable for secondary Class 1 National Insurance. A one-person company with a single director on payroll cannot claim it. Only one payroll per organisation can claim, and within a group only one company can claim. From April 2025 employers with more than £100,000 of Class 1 National Insurance liabilities face different eligibility rules.
Dividends. Not deductible against Corporation Tax; paid from post-tax profits. For 2026 to 2027 the dividend allowance is £500 and the rates are 10.75%, 35.75% and 39.35%. Dividends can only be paid from distributable profits, must be properly declared, and need board minutes and dividend vouchers. A dividend paid when there were no distributable profits is unlawful and can be reclaimed from you.
Employer pension contributions. A company contribution to a registered pension scheme is generally an allowable business expense, so it avoids both the dividend layer and National Insurance. There are annual allowance limits and rules on what is "wholly and exclusively" for the business, and both change; check the current GOV.UK annual allowance page before setting a contribution level rather than relying on a figure from an article. This guide deliberately does not print one.
For most owner-directors the standard structure is a modest salary plus dividends, with pension contributions where cash allows. The optimal split moved in April 2026 when dividend rates rose, so if you set your salary and dividend policy before then, it is worth revisiting.
Expenses, Simplified Expenses and Capital Allowances
You reduce tax by deducting real costs, not by inventing them.
Allowable expenses for the self-employed include office costs such as stationery and phone bills, travel including fuel, parking and fares, uniforms, staff and subcontractor costs, stock and raw materials, financial costs such as insurance and bank charges, premises costs including heating, lighting and business rates, marketing and website costs, and training courses related to your business. Where something has both a business and a personal use, only the business proportion is allowable. And you cannot claim expenses at all if you are using the £1,000 trading allowance.
Simplified expenses let you use flat rates instead of working out actual costs, for vehicles, working from home and living on business premises. The current mileage rates, which changed on 6 April 2026, are:
- Cars and goods vehicles, first 10,000 business miles: 55p per mile.
- Cars and goods vehicles, after 10,000 miles: 25p per mile.
- Motorcycles: 24p per mile.
Before 6 April 2026 the first-10,000-mile rate was 45p, so anyone still using 45p is now understating their claim. HMRC's own worked example: 11,000 business miles gives 10,000 at 55p, which is £5,500, plus 1,000 at 25p, which is £250, for £5,750.
Working from home flat rates, available only if you work 25 hours or more a month from home:
- 25 to 50 hours a month: £10 a month.
- 51 to 100 hours a month: £18 a month.
- 101 hours or more a month: £26 a month.
These rates do not cover telephone or internet costs, which you claim separately by working out the actual business proportion. For most home-based one-person businesses the flat rate is small enough that calculating actual costs is worth the effort, particularly if you have a dedicated room.
Capital allowances. The Annual Investment Allowance is £1 million and has been since 1 January 2019, for sole traders, partnerships and companies. It lets you deduct the full value of qualifying plant and machinery from your profits before tax. You cannot claim it on cars, on items you owned before using them in the business, or on gifts.
Where the "Rich" Part Comes In: Wrappers, Not Tricks
Once a business is throwing off surplus cash, the question becomes what to do with it. Two allowances do most of the work in the UK, and both are boring by design.
The ISA allowance for 2026 to 2027 is £20,000 across all ISA types: cash, stocks and shares, innovative finance, and Lifetime ISA. Returns inside an ISA are free of Income Tax and Capital Gains Tax, and there is nothing to report on your tax return.
That matters more than it used to because the Capital Gains Tax annual exempt amount for 2026 to 2027 is £3,000. Outside a wrapper, gains above £3,000 are taxed at 18% within the basic rate band and 24% above it, with the basic rate band at £37,700. From 6 April 2026, Business Asset Disposal Relief gives 18% for qualifying gains of sole traders, partnerships and trustees. If you are building a business you might eventually sell, that trajectory is worth watching, because the relief has become steadily less generous than it once was.
The unglamorous conclusion is that for most people the tax-efficient sequence is: get the compliance right so you are not paying penalties and interest at 7.75%, take the employer pension match if you have one, use the ISA allowance, and only then worry about anything more complicated. Schemes that promise to beat this are usually either an arrangement HMRC has already named, or a risk transfer dressed up as a tax saving.
A Twelve-Month Operating Calendar
Put these in a calendar with reminders a fortnight ahead. Most penalties in this guide are avoided by a diary entry.
- 5 April: tax year ends. Take stock of profits, decide on any pre-year-end pension contribution or equipment purchase.
- 7 May: Making Tax Digital quarterly update deadline for the period ending 5 April.
- 31 May: if you employ anyone, P60s are due to employees.
- 6 July: P11D deadline for benefits in kind, if applicable.
- 31 July: second payment on account due.
- 7 August: MTD quarterly update for the period ending 5 July.
- 5 October: deadline to register for Self Assessment for the tax year that ended the previous April. This is the one with the percentage-of-tax penalty.
- 31 October: paper Self Assessment return deadline.
- 7 November: MTD quarterly update for the period ending 5 October.
- 30 December: deadline to file online if you want a balance collected through your PAYE code.
- 31 January: online Self Assessment return, balancing payment, and first payment on account, all on the same day.
- 7 February: MTD quarterly update for the period ending 5 January.
- Company-specific, floating: confirmation statement each 12-month period at £50; accounts to Companies House 9 months after year end; Corporation Tax 9 months and 1 day after the accounting period; Company Tax Return 12 months after the accounting period.
Expensive Mistakes, Ranked by How Often They Happen
Assuming the trading allowance is a profit allowance. It is gross income. Over £1,000 gross means registration by 5 October, whatever your profit was.
Not setting money aside. The 31 January bill in your second profitable year is roughly 150% of your first year's liability because of payments on account. If you have spent it, you are borrowing at 7.75% from HMRC.
Watching the wrong VAT period. The backward look is a rolling 12 months, not your financial year. Businesses cross the threshold in month seven of a good year and notice in month twelve.
Joining the Flat Rate Scheme without the limited cost test. At 16.5% with no input VAT recovery, most consultants lose money on it.
Deciding your own IR35 status and not writing anything down. When the client is small the responsibility is yours, and an undocumented decision is indefensible three years later.
Treating the company bank account as your own. Undocumented withdrawals become director's loans with their own tax charges, and dividends paid without distributable profits are unlawful.
Missing a Companies House deadline twice. The penalty doubles for two successive late financial years. A £1,500 penalty becomes £3,000.
Ignoring identity verification. Since 18 November 2025 an unverified director acting as a director commits an offence, and so do the company and the other directors.
Assuming Making Tax Digital does not apply because turnover is small. Qualifying income combines gross self-employment and gross property income, and the April 2028 tranche at over £20,000 is tested on the tax year you are in right now.
Waiting for HMRC to find you. The gap between an unprompted and a prompted disclosure of a non-deliberate failure to notify is the difference between a possible 0% penalty and a floor of at least 10%.
Who should skip this
Being direct about this is more useful than encouragement.
People who need money this month. Every route described here is slow. Registering as a sole trader takes an afternoon; getting paid reliably takes many months. If your problem is next week's rent, employment solves it and self-employment does not. Self-employment also removes Statutory Sick Pay and makes your income lumpy, which is the opposite of what an acute cash problem needs.
People who will not keep records. Making Tax Digital removes the option of reconstructing a year from a shoebox each January. From your mandation date you must keep digital records and submit four times a year. If bookkeeping is something you are certain you will not do, either budget for someone to do it or do not take on the extra obligation.
People with a low tolerance for irregular income. Self-employed earnings are volatile, and the tax system asks you to prepay next year's tax based on last year's profits. A good year raises your payments on account into a bad year.
People hoping incorporation is a tax trick. After the April 2026 dividend rate rise, a basic-rate owner-director extracting everything as dividends is slightly worse off than a sole trader on tax alone, before the £50 confirmation statement, the accountancy fees and the filing risk. Incorporate for liability, for client requirements, or for genuine control over timing. Do not incorporate because of a headline rate comparison you read from before April 2026.
People who cannot pass identity verification, or who want to be invisible. Companies House verification is now mandatory and the register is public. Your name, month and year of birth, service address and shareholding are visible to anyone. If you need anonymity, a UK limited company is the wrong vehicle.
Anyone thinking of not declaring. The failure to notify penalty is a percentage of tax, deliberate and concealed behaviour reaches 100%, HMRC receives data from payment processors and online platforms, and interest runs at 7.75%. The arithmetic is bad and it gets worse with time.
Frequently Asked, Answered Precisely
Do I have to register the moment I make my first pound? No. If your gross trading income for the tax year is £1,000 or less and none of the four special reasons apply, you need not register. Above £1,000 gross, register by 5 October following the end of that tax year.
Sole trader or limited company, in one sentence? Sole trader for simplicity and for basic-rate profits you need to spend; limited company for liability protection, for clients who insist on it, and for the ability to leave profit in the business and choose when to take it.
How much does a limited company really cost per year? £50 for the confirmation statement, plus accountancy. Accountancy for a simple one-person company is commonly quoted somewhere around £600 to £1,500 a year, but that band is an estimate from how the market is typically priced, not a published figure. Get quotes.
Should I register for VAT voluntarily? Usually yes if your customers are VAT-registered businesses and you have real input VAT. Usually no if you sell to consumers, because you cannot pass the 20% on without becoming more expensive.
When does Making Tax Digital apply to me? Over £50,000 qualifying income in 2024 to 2025 means you should already be in as of 6 April 2026. Over £30,000 in 2025 to 2026 means April 2027. Over £20,000 in 2026 to 2027 means April 2028. Qualifying income is gross self-employment plus gross property income.
My client is a small company, so IR35 does not apply, right? Wrong. The rules still apply; what changes is that you, through your intermediary, are the one who must determine status, and you carry the risk. Use CEST, keep the output, keep the contract, and make sure your working practices match what you told the tool.
Is Class 2 National Insurance still a thing? Yes, but reshaped. At profits of £7,105 or more for 2026 to 2027 it is treated as paid without a bill. Below that you can pay voluntarily at £3.65 a week, which is the cheapest route to a qualifying year against Class 3 at £18.40.
What is the single most expensive mistake? Late registration combined with late payment. You can face a failure to notify penalty as a percentage of tax, late filing penalties starting at £100 and escalating, late payment penalties at 5% intervals, and interest at 7.75%, all on the same liability.