FREE UK Side-Hustle Tax Calculator 2026/27 – Do I Need to Tell HMRC? Trading Allowance & MTD Check (Excel)

Selling on Etsy, eBay or Vinted, or earning a bit on the side, and not sure whether HMRC needs to know? This free one-page spreadsheet gives you a quick answer for the 2026/27 tax year (6 April 2026 to 5 April 2027), based on GOV.UK rules checked in October 2026.

Type in five numbers and it tells you:

- whether the £1,000 trading allowance or your actual costs gives you the bigger deduction

- your estimated taxable profit

- whether you need to register for Self Assessment, and the deadline (5 October 2027)

- whether Making Tax Digital for Income Tax applies to you (the £20,000 threshold for 2026/27, starting 6 April 2028)

- whether a selling platform is likely to report your sales to HMRC (30 or more sales, or about £1,700 / €2,000)

- a rough Income Tax and Class 4 National Insurance figure, and how much to put aside each month

- the key dates: 5 Oct 2027, 31 Jan 2028 and 6 Apr 2028

Works in Excel 2016 or later, Microsoft 365 and Google Sheets. No macros. Includes a one-page quick-start PDF.

Want it tracked all year? The UK Side-Hustle & Online Seller Profit + Tax Tracker (£14) logs every sale and cost and builds your quarterly totals: https://payhip.com/b/QeiM0

This is a rough guide, not tax advice. The Income Tax estimate uses the England, Wales and NI bands.