Self Assessment Spreadsheet UK

Keep your sole trader records for the 2025/26 tax year (6 April 2025 to 5 April 2026) in one spreadsheet, and see roughly what you'll owe before the 31 January 2027 deadline.

What's inside

• Income log: every payment received, with dates outside the tax year flagged.
• Expenses log: pick a category that follows the self-employment (short) pages of the return, with non-allowable costs kept separate and a receipt check.
• Mileage log: HMRC simplified-expenses flat rates for 2025/26 calculated for you (cars and vans 45p for the first 10,000 business miles, then 25p; motorcycles 24p).
• Use of home: enter your hours each month to claim the simplified flat rate (£10, £18 or £26 a month).
• Summary: totals by category, your profit, and whether the £1,000 trading allowance beats your actual expenses.
• Tax estimate: Income Tax and Class 4 National Insurance at 2025/26 rates, plus what's due on 31 January 2027 and 31 July 2027, including payments on account.
• Deadlines: every key date with a live "days left" countdown.

Good to know

• The tax estimate uses rates for England, Wales and Northern Ireland and assumes self-employment is your only income. Scottish income tax rates are different.
• This is a record-keeping and estimating tool, not tax advice and not HMRC-recognised filing software. You still file your return on GOV.UK.
• Making Tax Digital for Income Tax starts from 6 April 2026 for some sole traders (qualifying income over £50,000), which affects the 2026/27 tax year onwards, not this 2025/26 return.

Works with

Microsoft Excel, Google Sheets (free) and Apple Numbers.