If you need to file a Self Assessment return for 2025/26 and have not registered before, you must tell HMRC by 5 October 2026.
01 / THE KEY DATES
When do you need to tell HMRC?
Your online 2025/26 tax return is due by 31 January 2027. Any tax you owe is generally due by the same date.
The £1,000 trading allowance is based on gross income
Gross trading income means turnover before expenses, not profit after expenses. If your gross trading income is £1,000 or less, you usually do not need to register for Self Assessment for that income alone. If it is more than £1,000, you generally need to register and report it. Other income or circumstances can mean you need to file for another reason.
02 / A QUICK CHECK
Does the 5 October deadline apply to you?
Answer three questions. This check is a guide, not a decision from HMRC.
Answer all three questions to see your likely next step. Your answers are not saved.
03 / NEXT STEPS
Get your records in order.
Check the trading allowance rules and use a checklist to prepare for filing.
FREE PDF CHECKLIST
The deadlines, without the dread.
Get the free 2025/26 Self Assessment deadline checklist (PDF) by email. A simple reminder of what to do and when.