ExpenseCatcher
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Allowable expenses tax saving calculator

For sole traders filing Self Assessment for 2026 to 2027 (6 April 2026 to 5 April 2027). Enter your turnover and expenses to see what claiming them saves, and what every lost £100 receipt costs you.

These are example numbers. Change them to yours.

Scotland has its own Income Tax rates.

What customers paid you, before expenses.

Supplies, software, travel, marketing and so on. Add your mileage and working from home allowances too.

A salary uses up your Personal Allowance and lower bands first.

Claiming £6,000 of expenses saves you about

£1,560

That’s about 26p of tax for every pound of expenses.

Income Tax
£1,200
Class 4 National Insurance
£360
Total saved
£1,560

Your estimated 2026/27 Income Tax and Class 4 National Insurance: £8,432 without expenses, £6,872 with them.

Every £100 receipt you lose costs you about £26 in extra tax.

ExpenseCatcher files every emailed receipt in your Google Drive and logs it in a Google Sheet, so none go missing at tax time. Start free

How it works

We work out your Income Tax and Class 4 National Insurance twice: without your expenses and with them. The difference is your saving. That way the Personal Allowance, the tax bands and the allowance taper above £100,000 all count.

Class 4 National Insurance is 6% of profits between £12,570 and £50,270 and 2% above that. Class 2 is no longer charged, so it doesn’t change with expenses. If you live in Scotland you pay Scottish Income Tax rates; National Insurance is the same everywhere.

It treats a salary as your only other income and leaves out pension contributions, Gift Aid, student loan repayments and losses. It’s an estimate to help you see the size of the numbers, not tax advice.

Questions

How much tax does £100 of expenses save?
For a typical basic-rate taxpayer in England, Wales or Northern Ireland, £26: 20% Income Tax plus 6% Class 4 National Insurance. For a typical higher-rate taxpayer, £42 (40% plus 2%). Between £100,000 and £125,140 it’s more, because expenses also win back Personal Allowance. Scottish rates differ.
Can I claim the £1,000 trading allowance as well?
No, it’s one or the other. The trading allowance lets you deduct £1,000 without receipts instead of your actual expenses. If your expenses are under £1,000, the calculator shows whether the allowance would save more.
What are allowable expenses?
Costs you have only for running your business, such as office supplies, software, travel, stock and marketing. If something is partly personal, like a phone, you claim only the business share.
How long do I keep receipts?
At least 5 years after the 31 January submission deadline for the tax year. Since April 2026, sole traders with qualifying income over £50,000 must also keep digital records under Making Tax Digital for Income Tax; the threshold drops to £30,000 in April 2027 and £20,000 in April 2028.

Sources

Figures checked against these sources on 5 November 2026. Estimates only, not tax advice: check your own return with a tax professional.

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