Had an HMRC letter about your rental income? Here's what it means.

What your HMRC letter really means.Understand it thoroughly before you reply.

A letter from HMRC is unsettling — whether it’s a gentle nudge, a formal HMRC enquiry, or an HMRC investigation. Many are far less alarming than they first appear, and this page helps you tell which is which.

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No obligation. We’re not your tax agent; this starts a conversation, not a commitment.

Whatever has landed on your doormat, the first move is the same: don’t ignore it, take a moment, and make sure you understand exactly what it is before you reply.

What kind of HMRC letter have you got?

You don’t need to send us anything, and you never upload your letter here. Look at your own letter and note: who it’s from within HMRC, the reference it mentions, whether it asks you to do something or simply check your position, and the response date printed on it.

The three kinds of letter — recognise and understand yours

HMRC letters come in three broad types. For each, here’s what it looks like, what it actually is, why you got it, and — honestly — what happens if you do nothing. No jargon.

1 · The “nudge” letter

The gentlest kind — a prompt, not an accusation.

Example only
HM Revenue & Customs — rental income

“Our records suggest you may have received income from property that has not been included on a tax return. We are writing to give you the opportunity to bring your tax affairs up to date…”

Illustrative wording only — not a real HMRC letter. The tell-tale sign of a nudge: it invites you to check, rather than opening a formal enquiry.

What it is
HMRC saying, in effect, “we think you might have rental income you haven’t told us about — please check and put it right if needed.” An invitation, not a formal investigation.
Why you got it
HMRC gets data from letting agents, the Land Registry, deposit schemes, banks, even other countries. If their records suggest you’ve let a property but not declared the income, a computer flags it. Usually they have a hint, not the full picture.
What it means
A chance to come forward on the best possible terms. Sorting it now, voluntarily, almost always means a smaller penalty than if HMRC has to chase you.
If you do nothing
It won’t disappear. Ignoring it can turn a low-penalty situation into a formal enquiry. And once HMRC has been in touch, a disclosure is harder to treat as fully “unprompted” — which can mean higher penalties. So act quickly, while you’re still in the strongest position. Doing nothing is the one move that makes things worse.

2 · An enquiry (a “check”)

More serious — HMRC is formally looking at your return.

Example only
HM Revenue & Customs — check of your tax return

“I am writing to tell you that I intend to check your Self Assessment tax return for the year ended 5 April… Please send the information listed below by [date]…”

Illustrative wording only — not a real HMRC letter. The tell-tale sign: it says HMRC is checking a specific return, names a reference, and sets a firm date to reply by.

What it is
HMRC formally opening a check into a specific tax return, asking questions and requesting documents, with a firm date to reply by.
Why you got it
Something on (or missing from) your return prompted a closer look — figures that don’t match HMRC’s data, or rental income they believe wasn’t declared. It can be random, but usually there’s a reason.
What it means
Where getting it right matters most, and where professional help is most valuable. What you say and send shapes the outcome. It doesn’t automatically mean trouble — but it’s not something to wing. How far back HMRC can go depends on the behaviour involved — a simple mistake is treated very differently from something deliberate.
If you do nothing
Missing the reply date can trigger a penalty in its own right, and HMRC can compel your records with an “information notice” — more penalties for non-compliance. Always respond by the date, even if only to ask for more time.

3 · An investigation (COP8 or COP9)

The serious end — get specialist advice before you do anything.

Example only
HM Revenue & Customs — Code of Practice 8 / 9

“This letter is issued under Code of Practice 9. HMRC has information that leads us to suspect… You are offered the opportunity to make a disclosure under the Contractual Disclosure Facility…”

Illustrative wording only — not a real HMRC letter. If you see “Code of Practice 8”, “Code of Practice 9” or “Contractual Disclosure Facility”, stop and get specialist advice before doing anything.

What it is
A deeper, formal investigation, in two forms: COP8 — a serious civil investigation where HMRC does not allege fraud; and COP9 — a fraud investigation, offering a special route (the Contractual Disclosure Facility) to come clean.
Why you got it
HMRC believes there’s significant tax at stake (COP8), or has information suggesting deliberate under-declaration or fraud (COP9). Not sent lightly.
What it means
There are legal protections and real risks that only a specialist can navigate for your situation. In general terms, the Contractual Disclosure Facility used in COP9 cases is designed to offer a route to resolve suspected fraud without criminal prosecution where the person makes a complete and accurate disclosure — but how it applies to your circumstances is a question only a qualified adviser can answer, and getting it wrong can go very badly. This is general information, not advice about your position — take specialist advice before you do anything.
If you do nothing
This is the flip side of that trade-off: the protection a COP9 disclosure can offer depends on cooperating fully and honestly. Ignoring the letter, or refusing to engage, can lose that protection and leave criminal prosecution on the table — which makes this the worst kind to ignore, and the one where the right specialist, early, makes the biggest difference. Do not respond, and do not prepare anything yourself — get specialist advice first. Get specialist advice →

Not sure which you’ve got? That’s completely normal. Answer a few plain questions and we’ll help you place your letter.

A few words explained

If some of the terms above are new to you, here’s what they mean — in the plainest terms.

Self Assessment
The system where you tell HMRC about income they don’t already know about — like rental income — usually once a year. If you’ve only ever been paid through a job (PAYE), your tax was handled for you and you may never have used it.
Tax return
The form (usually filed online) where you report that income for the year and work out the tax. A “Self Assessment tax return” is just that yearly form.
“Unprompted” vs “prompted” disclosure
If you come forward before HMRC contacts you, that’s unprompted — and it’s treated more kindly, with lower penalties. If you only put things right after HMRC gets in touch, that’s prompted, and penalties tend to be higher. That’s why acting early matters.
Information notice
A formal, legal request from HMRC telling you to hand over specific records or information. Unlike a polite ask, you can be penalised for not complying, so these shouldn’t be ignored.
A “declaration”
A formal statement, signed by you, that something is true. It carries legal weight — which is why signing one you’re not sure about is risky.

Note your real response date

Every HMRC letter sets its own deadline, printed on the letter itself. There is no universal countdown — ignore any website implying a fixed number of days for everyone. Read the date from your letter and work back from there.

Were you asked to sign a certificate?

Some HMRC letters enclose a “certificate of tax position” asking you to sign a declaration. These often follow overseas data HMRC has received, so if you have a property or bank account abroad, you’re more likely to see one. There is no legal obligation to sign it — but ignoring the letter is not wise either. And one thing you must know before signing: a certificate that is signed but not true can be a criminal matter, so it should never be signed carelessly. You are entitled to decline to sign it — that is a legitimate choice, not defiance. And note: signing the certificate is not the same as putting things right — it’s only a declaration about your position, not a disclosure. If your affairs are not in order, the safer path is almost always a proper disclosure rather than signing a declaration that they are fine. This is information, not advice on which box to tick.

Why responding well can save you thousands

A letter isn’t just something to survive — how you handle it directly affects what you end up paying. The outcome is largely in your hands:

  • Come forward before it becomes formal. If a nudge letter is really flagging undeclared tax, a voluntary, unprompted disclosure can cut the penalty dramatically — sometimes to nothing — compared with waiting for a formal enquiry.
  • Respond by the date, and respond right. Missing a deadline or answering badly can add penalties and widen the enquiry. Reading the letter correctly and replying calmly, in full, keeps things smaller.
  • Know which letters you can handle yourself. A nudge or a routine check is usually something a capable landlord can deal with unaided; only the serious ones (COP8/COP9) genuinely need a specialist — and this page helps you tell which is which.

You’ve got this

A letter from HMRC feels frightening — but it’s not a verdict, and whatever it says, there’s a clear way to respond.

Take a breath. Understand what you’ve got, don’t rush, and don’t ignore it. Most letters — a nudge, or a routine check — are far more manageable than they first appear, and you can usually handle them yourself: read it carefully, work out what it’s really asking, and respond calmly by the date on it. The tools here help you do exactly that. Only the serious ones (a COP8 or COP9 investigation) genuinely need a specialist — and this page helps you tell which is which. You don’t have to work it all out today. You just have to take the first step.

  • A letter is not a verdict
  • Understand it before you reply
  • One step at a time, at your pace

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