Tax · United Kingdom
Notice to complete a tax return (SA316) — HMRC expects a return from you
The SA316 is HMRC's formal notice that a Self Assessment tax return is expected from you for the stated tax year. Once served, the duty to file exists even if you believe you owe no tax — unless HMRC agrees to withdraw the notice.
How serious: needs actionAlso called: SA316, Notice to file, Self Assessment notice
The SA316 tells you HMRC expects a Self Assessment tax return for the named tax year. Per HMRC's manual, 'SA paper returns and SA316 (Notice to complete a tax Return) are issued annually on or after 6 April following the end of the tax year to which they relate' — usually to people who previously filed online.
The notice is what creates the filing duty. Once served, the obligation exists even if you believe you owe no tax. The only way it goes away is if HMRC agrees to withdraw the notice.
Two dates follow from it: a filing deadline for the return and a payment deadline for any tax due. Missing the filing deadline triggers an automatic £100 penalty, whether or not tax is owed.
Who sends it
HM Revenue and Customs (HMRC), the UK's tax authority.
An HMRC letter, or a message in your personal tax account, headed 'Notice to complete a tax return' with the reference SA316. It names the tax year and your UTR and arrives in April or May.
The deadline
Paper return by 11:59pm on 31 October following the tax year; online return by 11:59pm on 31 January; tax owed also due by 31 January. If HMRC notifies you late (the current gov.uk wording covers registering after 5 October): 'this will be 3 months from the date on the letter or email', but 'You must still pay the tax you owe by 11:59pm on 31 January... or you'll get a penalty.'
A paper return is due by 11:59pm on 31 October following the tax year; an online return by 11:59pm on 31 January; tax owed is also due by 31 January. These run from the end of the tax year on 5 April. If HMRC notifies you late (the current gov.uk wording covers registering after 5 October), the filing deadline is '3 months from the date on the letter or email' — but 'You must still pay the tax you owe by 11:59pm on 31 January... or you'll get a penalty.'
If you do nothing
Missing the filing deadline triggers 'an initial £100 penalty' automatically, even if no tax is owed. After 3 months, '£10 per day, up to a maximum of £900' is added. At 6 months comes 'a further penalty of 5% of the tax due or £300, whichever is greater', and 'another 5% or £300 charge' at 12 months. Late payment adds 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest. If no return ever arrives, HMRC can make a determination of your tax 'to the best of his information and belief' — with no right of appeal.
Compute your date
The rule above is what the law sets. Put in the dates on your own letter and it becomes a date.
Don't miss this date
We'll email you 7, 3 and 1 day before, and on the day — at 9:00 your time.
We keep only what the reminder needs — type, dates, sender — encrypted. Delete it any time.
How it escalates
- 01Day after the filing deadline: automatic £100 late filing penalty (notice SA326D).
- 023 months late: daily penalties of £10 a day, up to £900.
- 036 months late: a further penalty of 5% of the tax due or £300, whichever is greater; repeated at 12 months.
- 04Late payment: 5% of the unpaid tax at 30 days, 6 months and 12 months, plus interest.
- 05Eventually HMRC can issue a revenue determination — a binding estimate of your tax with no right of appeal — and enforce it as a debt.
How to respond
Response types
- Confirm receiptFile the Self Assessment return in answer to the notice · Taxes Management Act 1970, s.8 (personal return) - the notice to file is given under this section
- Ask for clarificationRequest withdrawal of the notice to file (s.8B TMA 1970) · Taxes Management Act 1970, s.8B (withdrawal of notice under s.8 or s.8A)
- Ask for instalmentsTime to Pay arrangement for the tax shown by the return
Where and how
- File your Self Assessment tax return online
- Post (first class / ordinary mail)
- Royal Mail Signed For / Special Delivery Guaranteed
- Telephone
What makes it count
Filing online is timestamped and is the safest route: the return counts as delivered when HMRC's service accepts it, up to 11:59pm on the deadline day. A paper return must physically reach HMRC by 31 October - posting on the deadline is not enough - so send it early and keep proof of posting. The 3-month rule for a late-issued notice runs from the date printed on HMRC's letter or email, not from receipt, and the 31 January payment date is unaffected by it.
Common questions
I owe no tax. Do I still have to file?
Yes, once the notice is served, unless HMRC agrees to withdraw it. The £100 late filing penalty applies even when no tax is owed.
What are the deadlines?
Paper return by 31 October, online return by 31 January, and any tax due by 31 January — all following the end of the tax year on 5 April.
The notice reached me late. Does that change the deadline?
Per gov.uk, a late notification gives 3 months from the date on the letter or email to file. The tax itself must still be paid by 11:59pm on 31 January.
What happens if I never file?
Penalties climb from £100 to daily and percentage charges, and HMRC can issue a revenue determination — an estimate of your tax with no right of appeal — and enforce it as a debt.
Sources
Facts verified against the sources below on 28 August 2026.