VAT and Your Self-Assessment Return: How the Two Interact

Once you are VAT registered, your self-assessment return must show turnover and expenses net of VAT, because the VAT you charge customers is never your income and the VAT you pay suppliers is never your expense. The VAT registration threshold UK 2026 sits at £90,000 of taxable turnover measured over any rolling 12-month period, and crossing it changes both what you owe HMRC each quarter and what you report each January. Sole traders who miss the distinction routinely overstate their profit and pay income tax on money that was only ever passing through their bank account. Blue Tick Accountants, a Guildford-based UK tax advisory and accountancy practice, sees this error more often than almost any other on self-employed returns. This article explains when registration becomes compulsory, exactly how registration changes the figures on your tax return, how the flat rate scheme creates taxable profit, whether voluntary registration is worth it, and the cash flow traps that catch newly registered sole traders.

Key Takeaways

• The VAT registration threshold is £90,000 of taxable turnover in any rolling 12-month period for 2026/27, and the deregistration threshold is £88,000.
• A VAT-registered sole trader reports turnover and expenses excluding VAT on the self-assessment return, so VAT collected from customers never forms part of taxable profit.
• A sole trader who is not VAT registered reports gross figures, including any VAT charged by suppliers, because that VAT is an irrecoverable cost.
• Under the VAT flat rate scheme, turnover is reported including VAT and the flat rate payment is deducted as an expense, so any surplus retained is taxable income.
• Registration must be notified to HMRC within 30 days of the end of the month in which the £90,000 threshold was crossed, and takes effect from the first day of the second month afterwards.
• From 6 April 2026, sole traders with qualifying income above £50,000 must file quarterly Making Tax Digital updates in addition to their VAT returns, with a final declaration due by 31 January.

When Must a Sole Trader Register for VAT in 2026/27?

A sole trader must register for VAT when taxable turnover exceeds £90,000 in any rolling 12-month period, or when turnover is expected to exceed £90,000 in the next 30 days alone. The rolling test is the one that catches people out: it is not your accounting year, and it is not your profit. HMRC expects you to check the previous 12 months at the end of every month.

Knowing when to register for VAT self-employed workers must apply the test to taxable supplies only, so exempt income such as some financial or educational services is excluded, but zero-rated sales still count. Once the threshold is crossed, you have 30 days from the end of that month to notify HMRC. Late notification carries a penalty based on the VAT that should have been charged, and HMRC will still expect that VAT even if you never collected it from your customers. For a full overview of the registration process and the schemes available, see our guide to VAT registration.

How Does VAT Registration Change the Figures on Your Tax Return?

VAT registration means your self-assessment turnover figure falls, because you report sales net of the VAT you charge and expenses net of the VAT you reclaim. Your income has not changed, but the amount HMRC taxes as profit is now measured on the money that genuinely belongs to your business.

Worked example: a Guildford-based designer invoices £108,000 during 2026/27, made up of £90,000 of fees plus £18,000 of VAT, and incurs £28,800 of costs comprising £24,000 net plus £4,800 of recoverable VAT. The correct self-assessment entries are turnover £90,000 and expenses £24,000, giving a taxable profit of £66,000. Entering the gross figures instead would produce a profit of £79,200, overstating it by £13,200. For a higher-rate taxpayer that mistake costs an extra £5,544 in income tax and Class 4 National Insurance for a single year. The same principle applies in reverse to sole traders below the VAT threshold sole trader limit, who correctly claim their expenses gross because the VAT they pay is not recoverable.

How Does the Flat Rate Scheme Affect Your Taxable Profit?

The VAT flat rate scheme changes the accounting treatment entirely: turnover is reported on the self-assessment return including VAT charged, and the flat rate payment made to HMRC is deducted as a business expense. Any difference between the VAT you collect and the flat rate you pay over is retained by the business and forms part of your taxable profit.

Worked example: a consultant on a 14.5% flat rate invoices £60,000 plus £12,000 of VAT. The flat rate payment is 14.5% of the £72,000 gross, or £10,440. Turnover reported is £72,000, the flat rate payment of £10,440 is claimed as an expense, and the £1,560 surplus is taxed as profit alongside everything else. The scheme is open to businesses with taxable turnover of £150,000 or less excluding VAT, and input VAT cannot generally be reclaimed, other than on single capital assets costing £2,000 or more including VAT.

Is Voluntary VAT Registration Worth It Below the Threshold?

Voluntary VAT registration below £90,000 is usually worthwhile when your customers are VAT-registered businesses, and usually harmful when your customers are consumers. Registered business customers reclaim the VAT you charge, so your prices are effectively unchanged while you recover VAT on your own costs. Private consumers cannot reclaim anything, so adding 20% either raises your price or cuts your margin.

Worked example: a sole trader supplying VAT-registered companies spends £14,000 a year on standard-rated costs. Voluntary registration recovers £2,333 of input VAT annually at no commercial cost to the client base. The same trader selling to households would need to absorb roughly £15,000 of VAT on £90,000 of sales, or push prices up by a fifth. Registration also allows recovery of VAT on goods bought in the four years before registration and services in the six months before, which can produce a useful opening claim.

What Does VAT Do to Your Cash Flow and Filing Deadlines?

VAT registration adds a quarterly payment cycle on top of your existing self-assessment dates, and the VAT you collect is never available to spend. Most sole traders file and pay VAT one month and seven days after each quarter end, while income tax remains due on 31 January and 31 July.

The cash accounting scheme, open to businesses with taxable turnover up to £1.35 million, lets you account for VAT only when customers actually pay, which protects you from funding VAT on unpaid invoices. Separately, Making Tax Digital for Income Tax now applies from 6 April 2026 to sole traders with qualifying income above £50,000, requiring digital records, four quarterly updates and a final declaration by 31 January. The threshold falls to £30,000 from April 2027 and £20,000 from April 2028. A VAT-registered sole trader above £50,000 therefore has two separate digital filing obligations running in parallel, and HMRC treats them as entirely distinct.

Frequently Asked Questions

Does VAT count as income on my self-assessment return?

No. VAT charged to customers is collected on behalf of HMRC and never counts as income on a self-assessment return. A VAT-registered sole trader reports turnover excluding VAT and expenses excluding recoverable VAT. The only exception is the flat rate scheme, where gross turnover is reported and the flat rate payment is claimed as an expense.

What is the VAT registration threshold for a sole trader in 2026/27?

The VAT registration threshold is £90,000 of taxable turnover in any rolling 12-month period for 2026/27. Registration is also compulsory if you expect to exceed £90,000 within the next 30 days alone. The threshold is measured on taxable sales, not profit, and not on your accounting year.

Can I claim VAT as an expense if I am not VAT registered?

Yes. A sole trader who is not VAT registered claims expenses at the full gross amount paid, including any VAT charged by suppliers, because that VAT cannot be recovered. This is why unregistered traders show higher expense figures than registered traders buying identical goods.

When do I have to tell HMRC I have crossed the VAT threshold?

You must notify HMRC within 30 days of the end of the month in which your rolling 12-month turnover exceeded £90,000. Registration then takes effect from the first day of the second month after the threshold was crossed. Late notification triggers a penalty calculated on the VAT that should have been charged.

Does Making Tax Digital replace my VAT return?

No. Making Tax Digital for Income Tax and Making Tax Digital for VAT are separate obligations with separate filings. From 6 April 2026, sole traders with qualifying income above £50,000 must submit quarterly income tax updates and a final declaration by 31 January, alongside their existing quarterly VAT returns.

How Blue Tick Can Help

Blue Tick Accountants advises sole traders on VAT registration timing, scheme selection and the correct treatment of VAT within self-assessment and Making Tax Digital filings. A short review before you cross £90,000 usually identifies whether the flat rate or cash accounting scheme suits your business and prevents the overstated profit that costs thousands in unnecessary tax. Head to our website and book a meeting now.

Conclusion

VAT and self-assessment are separate systems that meet on one line of your tax return, and getting that line wrong is expensive in both directions. Check your rolling 12-month turnover at the end of every month rather than at your year end, and make sure your bookkeeping records sales and costs net of VAT from the day your registration takes effect. If you are approaching £90,000, decide on your scheme before registration rather than afterwards, because the choice permanently changes how your profit is calculated.

About the Author

This guide was written by Leon, founder of Blue Tick Accountants, a Guildford-based UK tax advisory and accountancy practice that helps self-employed people, landlords and limited company owners across the UK. It was last reviewed for the 2026/27 tax year.

This article is intended for general informational purposes only and does not constitute tax, legal, or financial advice. Tax rules are subject to change and their application will depend on your individual circumstances. You should always seek advice from a qualified professional before taking action. Blue Tick Accountants accepts no liability for decisions made on the basis of this content.