Tax · United Kingdom
Welcome to Self Assessment (SA250) — the letter with your UTR number
The SA250 is HMRC's confirmation that you are now registered for Self Assessment. It carries your 10-digit Unique Taxpayer Reference (UTR) and is not a bill — but it marks the start of your duty to file returns when asked.
How serious: routineAlso called: SA250, Welcome letter, UTR letter
HMRC sends the SA250 when you are first registered for Self Assessment — for example after starting self-employment or declaring untaxed income. It confirms the registration and gives you a 10-digit Unique Taxpayer Reference, the UTR.
The UTR is the number you need for everything that follows: filing returns, paying tax, appointing an accountant and dealing with HMRC. Losing the letter means losing easy access to it.
The letter is not a bill and asks for no payment. What it does is put you inside the Self Assessment system. From now on, when a return falls due, the filing and payment deadlines apply.
Who sends it
HM Revenue and Customs (HMRC), the UK's tax authority.
An HMRC letter titled 'Welcome to Self Assessment' with the form reference SA250 and a 10-digit UTR printed near the top. Recent versions may carry a QR code directing you to online services.
The deadline
None in the letter itself. Note the linked filing rule for late registrants — gov.uk: 'If you register after 5 October... HMRC will send you a letter or email with a different deadline to send your tax return by - this will be 3 months from the date on the letter or email', and 'You must still pay the tax you owe by 11:59pm on 31 January... or you'll get a penalty.'
The letter itself sets no deadline. One linked rule matters for people who register late — gov.uk: 'If you register after 5 October... HMRC will send you a letter or email with a different deadline to send your tax return by - this will be 3 months from the date on the letter or email'. The tax owed must still be paid 'by 11:59pm on 31 January... or you'll get a penalty.'
If you do nothing
Nothing immediate — the SA250 is confirmation of registration. But once registered you are in the Self Assessment system: when a return is due and not filed by the deadline, the automatic penalty ladder starts (£100, then daily penalties). Losing the letter means losing easy access to your UTR, which you will need for everything else.
How it escalates
- 01No direct consequence from the letter itself.
- 02If a tax return later falls due and is not filed, the automatic late-filing penalties apply: 'an initial £100 penalty', then '£10 per day, up to a maximum of £900' after 3 months, then 5% of the tax due or £300 at 6 and 12 months.
Common questions
Is the SA250 a bill?
No. It confirms your registration and gives you your UTR. Nothing is owed because of this letter.
What is the UTR for?
It is your 10-digit Unique Taxpayer Reference. It is needed to file returns, pay tax, appoint an accountant and contact HMRC.
I registered late — what is the deadline for my return?
Per gov.uk, if you register after 5 October, HMRC sends a letter or email with a different deadline: 3 months from the date on it. The tax itself is still due by 11:59pm on 31 January.
Sources
Facts verified against the sources below on 28 August 2026.