Side hustle Self Assessment guides
Plain-English, GOV.UK-checked guides for the 2025/26 tax year – return and payment due 31 January 2027.
- Self Assessment deadline 31 January 2027: what to file and pay
The 2025/26 online Self Assessment deadline is 11:59pm on 31 January 2027. What's due, payments on account, penalties and a countdown plan for side hustlers.
- Do I need to tell HMRC about my side hustle?
The £1,000 trading allowance, when you must register for Self Assessment, selling personal items vs trading, and what to do if you're late – for 2025/26.
- Etsy seller tax UK: what to declare for 2025/26
UK Etsy sellers: when Etsy income is taxable, the £1,000 rule, HMRC platform reporting, what counts as gross sales and which Etsy fees you can deduct.
- SA103S explained box by box (2025/26)
A plain-English walk through every box on the SA103S self-employment (short) pages for 2025/26: turnover, box 10.1 trading allowance, expenses 11–20 and NI.
- Trading allowance vs expenses: which saves you more tax?
The £1,000 trading allowance vs claiming actual expenses for UK side hustles in 2025/26, with worked examples, the rules and the catches.
Get your 2025/26 numbers sorted
January Sorted is a £17 spreadsheet tracker for UK side hustles: it compares the trading allowance with your expenses, estimates your tax, NI and payments on account, and lays out your SA103S figures box by box. Excel & Google Sheets.
Launch offer: 20% off with code JANUARY20 until 31 December.
Free: UK Self Assessment Checklist 2025/26
A 3-page, GOV.UK-checked checklist of every date, document and decision for your 31 January 2027 return. Free by email.