HMRC & Tax Letters

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HMRC letters can look alarming — but most are routine. The problem is knowing which ones actually need action, and what to do about it.

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Most HMRC letters are routine — a tax calculation, a new tax code, or a request for information — and only a minority ask you to pay a penalty or respond by a deadline. The trick is telling which is which, and HMRC's formal wording rarely makes that obvious.

Last reviewed: July 2026 · Information only, not legal advice

HMRC & Tax Letters at a glance

The common hmrc & tax letters and what each one means, how urgent it usually is, and the deadline to be aware of.

Letter	What it means	Typical deadline	Urgency
P800 tax calculation	HMRC has worked out you paid too much or too little tax for the year	Refunds: claim within the stated window. Underpayments: usually collected automatically	Low
Simple Assessment (PA302)	HMRC has calculated tax you owe and is asking you to pay it directly	31 Jan, or within 3 months if issued later	Medium
SA302 tax calculation	A summary of your Self Assessment income and tax — often needed to prove income for a mortgage	None — it is a record, not a demand	Low
Tax code notice (P2)	Explains the tax code your employer or pension will use, and how it was worked out	Check it is right; no action if correct	Low
Late filing penalty (SA326/SA370)	A £100 penalty because a Self Assessment return was filed late	Pay or appeal within 30 days	High
Compliance check / enquiry	HMRC is formally checking your tax return or records	Respond by the date in the letter	High

Common hmrc & tax letters explained

What does an HMRC P800 letter mean?

A P800 is a tax calculation showing HMRC thinks you either overpaid or underpaid Income Tax in a tax year. If you overpaid, the letter explains how to claim your refund (often online, or by cheque if you do nothing). If you underpaid, HMRC usually collects it automatically by adjusting your tax code the following year, so there is often nothing to pay upfront. A P800 is not a fine and not an accusation — it is HMRC reconciling the PAYE tax already taken from your wages or pension.

Is an HMRC letter a fine or a scam?

Genuine HMRC letters quote your reference numbers and never ask for payment by gift card, cryptocurrency, or an unusual bank transfer. A real penalty letter (for example a £100 late-filing penalty) states exactly what the penalty is for and how to appeal. If a letter demands immediate payment through unusual channels or threatens instant arrest, treat it as a likely scam and check it against gov.uk before doing anything.

Do I have to respond to an HMRC letter?

It depends on the type. A P800, an SA302, or a tax code notice is usually just information — you only act if a figure looks wrong. A Simple Assessment, a penalty notice, or a compliance check does need a response by the date stated. If in doubt, the safest step is to check the specific letter rather than ignore it, because HMRC deadlines carry penalties and interest.

Explain a specific letter

Guides to the individual letters people ask about most in this category:

P800 tax calculation A P800 is a tax calculation letter from HMRC showing that, after adding up your income ... SA302 tax calculation An SA302 is a document from HMRC that summarises your income and the tax you owe for a ... Simple Assessment (PA302) A Simple Assessment (sometimes shown as a PA302) is a letter where HMRC has worked out ... Self Assessment late filing penalty An HMRC late filing penalty is a charge because your Self Assessment tax return was not... Tax code notice (P2) A tax code notice (often called a P2 or 'PAYE coding notice') tells you the tax code HM...

What happens if you ignore hmrc & tax letters?

Ignoring a routine HMRC letter (like a P800 or tax code notice) rarely causes harm beyond missing a refund you were owed. But ignoring a Simple Assessment, penalty, or compliance check letter means penalties and interest build up, and HMRC can eventually collect the debt through your tax code, a debt collection agency, or court action. If you genuinely cannot pay, HMRC offers Time to Pay arrangements — contacting them early almost always improves your options.

Why these letters are so hard to understand

HMRC letters are written in formal, technical language that often makes them sound more urgent or serious than they are. Reference numbers, tax codes, and legal terminology make it hard to know whether you're being asked to do something, informed of something, or warned about something.

❓ Is this a fine or a penalty?

❓ Do I need to respond — and by when?

❓ What happens if I ignore it?

❓ Is my tax code correct?

❓ Am I being investigated?

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HMRC & Tax Letters: frequently asked questions

How do I know if an HMRC letter is genuine?

Genuine HMRC letters include your reference numbers, never demand payment by gift card or cryptocurrency, and can be cross-checked using the official "check a list of genuine HMRC contacts" guidance on gov.uk.

Will HMRC take money from my wages?

HMRC can collect tax you owe by adjusting your tax code (so a little more is taken from each payslip), and for unpaid debts it can use direct earnings attachment or debt collectors — but only after letters you can respond to first.

Can I appeal an HMRC penalty?

Yes. Most HMRC penalties can be appealed within 30 days if you have a reasonable excuse, such as serious illness or bereavement. The penalty letter itself explains how to appeal.

Official sources & free help

This page is written in plain English and checked against official guidance. For the full detail — and free, independent help — see:

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