Tax · United Kingdom
Revenue determination (section 28C, Taxes Management Act 1970) — HMRC's estimate when no return was filed
A revenue determination is HMRC's own estimate of the tax you owe, made because a Self Assessment return was required and never filed. It cannot be appealed. The only mechanism that replaces the figure is filing the actual return, within a time limit.
How serious: enforcement closeAlso called: Determination notice, HMRC determination, Section 28C determination
When you were required to file a Self Assessment return and did not, an HMRC officer can determine the amounts 'to the best of his information and belief'. That estimate is the revenue determination, made under section 28C of the Taxes Management Act 1970.
It is deliberately not appealable. Until the real return is filed, the estimate is fully enforceable as if you had declared it yourself. It also sets your payments on account for the next year.
The figure can be replaced, but only one way: by filing the actual return within the statutory window. Once that window closes, the estimate becomes final — even if the real figure would have been lower.
Who sends it
HM Revenue and Customs (HMRC), the UK's tax authority.
An HMRC letter stating that because your tax return for a named year was not received, HMRC has determined the tax due. It shows an estimated amount, a demand for payment, and wording that the determination stands until you send in your return.
The deadline
No appeal exists — 'There's no right of appeal against this estimate.' It can only be displaced by filing the actual return: a superseding self-assessment must be made within the s28C(5) limits — 'before the end of the period of 3 years beginning with the filing date' or, if later, 'before the end of the period of twelve months beginning with the date of the determination'.
There is no appeal: 'There's no right of appeal against this estimate.' The determination can only be displaced by filing the actual return — a superseding self-assessment must be made within the s28C(5) limits: 'before the end of the period of 3 years beginning with the filing date' or, if later, 'before the end of the period of twelve months beginning with the date of the determination'. The 12-month window runs from the date of the determination.
If you do nothing
The estimated tax is legally collectable: the determination 'shall have effect... as if it were such a self-assessment' until superseded by your real return. You 'still have to pay the amount due', and 'HMRC may take legal action to recover the amount due and any costs'. Once the supersession window closes, the estimate becomes final — even if the real figure would have been lower.
How it escalates
- 01The determined amount is enforced as an ordinary tax debt — HMRC's debt process applies: debt collection agencies, taking control of goods, direct recovery from bank accounts, court action.
- 02Late-filing penalties on the missing return continue to accrue separately.
- 03After the statutory window (12 months from the determination, if the 3-year limit has passed) the right to replace the estimate with your actual figures is lost permanently.
Common questions
Can I appeal the amount?
No. There is no right of appeal against the estimate. Filing the actual return is the only mechanism that replaces it.
How long do I have to file the real return?
Within 3 years beginning with the filing date, or, if later, within 12 months beginning with the date of the determination (s28C(5)).
Do I have to pay an estimate?
Yes. The determination has effect as if it were your own self-assessment until a real return supersedes it, and HMRC may take legal action to recover it.
Sources
Facts verified against the sources below on 28 August 2026.