Self Assessment guides for 2025-26
Plain-English help with the parts of the tax return people find hardest. Every guide uses HMRC's 2025-26 box numbers and has a worked example.
How to fill in the UK property pages (SA105)
Joint lets, the £1,000 allowance or actual costs, mortgage interest and every box from 1 to 45.
EmploymentClaiming job expenses (boxes 17 to 20)
Uniform and tool flat rates, business mileage at 45p, professional fees and working from home.
Self-employedThe Self-employment (short) pages
Turnover, the £1,000 trading allowance, expenses, taxable profit and Class 2 and 4 NI.
PayingPaying through your tax code
Owe under £3,000? File online by 30 December 2026 and spread it over 12 months.
PayingPayments on account explained
The £1,000 and 80% rules, why January can be 150% of your bill, and how to reduce them.
ReliefsHigher-rate pension and Gift Aid relief
Gross or net, which boxes to use, the £100,000 trap and Scottish rates.
Want your own figures? The free calculator turns your P60, rent, business and savings figures into the exact figure for every box.
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