5 October 2026: Register for Self Assessment
If you became self-employed, started renting out property or had untaxed income in the 2025/26 tax year and have not filed before, you must tell HMRC by 5 October 2026.
Is this you?
Anyone who needs to file a Self Assessment return for the first time for the tax year to 5 April 2026: new sole traders, new landlords, new company directors taking dividends, people with untaxed income over the reporting limits.
The detail
Registering gives you a Unique Taxpayer Reference and, for the self-employed, sets up your Class 2 and Class 4 National Insurance record. Register online through your Government Gateway account; the UTR arrives by post within about ten working days.
Registering is separate from filing. The return for 2025/26 is then due by 31 January 2027, so leaving registration late compresses the time you have to gather the figures.
What it costs
There is no fixed fine for registering late in itself, but you can be charged a "failure to notify" penalty based on the tax that ends up paid late, and the filing and payment deadlines do not move. If the UTR arrives after 31 January the return is late from day one.
Now
Register now if any of the above applied to you last tax year. If you are not sure whether you need to, ask: five minutes on a call settles it.
