Understanding HMRC letters
How to read an HMRC letter and what to do next, depending on which type you've received.
Articles
First rule: read the header, find the deadline
Every HMRC letter states what it is about, which tax and year it covers, and — the part that matters — what happens next and by when. The deadline is usually 30 days. Diarise it before you do anything else, because nearly every right you have depends on responding inside it.
Second rule: verify before you act. Genuine HMRC letters quote your reference numbers and never ask for card details or payment to unusual accounts. If in doubt, contact HMRC through the number on gov.uk, not the one on the letter.
The routine ones
Tax calculations (P800s), statements of account, payment reminders, and notices to file are administration, not accusation. Check the figures against your own records — P800s in particular are computer-generated and worth verifying before you accept a refund or a demand.
A notice to file a return is worth respect: once issued, the filing obligation exists even if you believe you owe nothing, until HMRC formally withdraws it.
The serious ones
A compliance check or enquiry letter opens a formal process — HMRC is asking questions about a return, and the scope stated in the letter matters. Penalty notices carry appeal rights with a 30-day clock. 'Nudge' letters — one-to-many campaigns saying HMRC has data suggesting undeclared income — are the modern precursor to enquiry: they invite you to correct your position before formal action.
None of these should be answered casually or ignored. What you say in a first response shapes the whole process; this is the point at which clients hand the letter to us.
Responding well
Answer what was asked, by the deadline, in writing, keeping copies. Volunteer accuracy, not narrative. If more time is genuinely needed, request it before the deadline rather than explaining afterwards.
RR clients forward HMRC letters to us on receipt — typically answered well inside the window, with the response framed correctly the first time.
Frequently asked questions
I've received a 'nudge letter' about undeclared income. Is it serious?
Yes — it means HMRC's data (agents, deposit schemes, banks, overseas exchanges) points at you. It is also an opportunity: correcting your position now, via disclosure, is treated far more gently than waiting for the formal enquiry that often follows silence.
How do I know an HMRC letter is genuine?
Genuine letters quote your UTR or NI number, relate to a real tax position, and direct payment only to HMRC's published accounts. HMRC does not demand payment by gift card, threaten arrest by text, or email you links to refunds. Verify through gov.uk contacts, not the letter's own details, when unsure.
What if I miss the deadline in the letter?
Respond anyway, immediately, and explain the delay. Some rights — notably the 30-day appeal window — can still be exercised late with a reasonable excuse, but every day of silence narrows the options and hardens HMRC's position.
Should I call HMRC or reply in writing?
Writing, for anything that matters — it creates the record the process will later rely on. Calls are fine for administration, but concessions and explanations given on the phone are hard to evidence and easy to misstate.