A nudge letter is HMRC telling you it holds information that suggests you may have income to declare, and inviting you to check. Many include a certificate of tax position asking you to declare that your affairs are correct, or that you will disclose. There is no legal duty to sign it. Signing a false declaration, even by mistake, can be treated as deliberate. The right response is to check your position properly, then either make a disclosure or write back explaining why nothing is due, without signing a certificate you cannot stand behind.
What the letter is and is not
A nudge letter is not an enquiry and not an accusation. It is a standard letter sent to everyone whose data pattern matches a risk, and HMRC sends thousands. It usually gives a deadline, typically 30 days, to respond. Ignoring it does not close the matter; HMRC may open a formal enquiry instead, which removes the benefit of coming forward voluntarily.
What a “certificate of tax position” actually is
The name sounds official and frightening, but it is simpler than it looks. It is a single printed page that HMRC puts in the envelope with the nudge letter. It is not a certificate in the everyday sense — nothing is being awarded to you. It is a form you are asked to sign and post back.
On the page there is a deadline (usually 30 days), then a short list of boxes. You are asked to tick one box and sign your name. The boxes say something close to this:
This is a plain example to show the shape of the form. Your certificate may use different words, and there is an offshore version and a UK version.
Here is the catch, in plain terms. A normal tax return covers one year. This form asks you to promise something about every year of your life at once, and there is no “too small to matter” line — even a tiny thing you forgot years ago could make your ticked box untrue. That is why you can end up in trouble for signing it even when you were trying to be honest.
Why the certificate matters
The certificate asks you to state, in writing, that your tax affairs are correct and complete. Two things make that riskier than it looks. It is not limited to one tax year like a normal return: it is a sweeping statement about every year of your affairs, with no lower limit below which a mistake is ignored. And the form itself warns that making a false statement is a criminal offence that can lead to investigation or prosecution. If a signed certificate later proves untrue, HMRC can also point to it as evidence that the error was deliberate, which raises the penalty scale and extends the look-back period. That is why professional advisers, and the Chartered Institute of Taxation, routinely recommend against signing it: HMRC has confirmed there is no legal obligation to. You can respond fully and honestly in a letter of your own instead.
If HMRC has alleged deliberate behaviour, or you have a Code of Practice 9 (COP9) letter, this is not the page for you: that is a serious matter needing specialist representation, not a checklist or a template reply. Read what COP9 means, then get specialist help before you respond.
How to respond
- Read the letter for the reason given. It often names the type of information HMRC holds, such as property ownership or a letting platform.
- Check your own position honestly: every property, every year, every source of rent.
- If something was missed, make a disclosure, usually through the Let Property Campaign, and say so in your reply.
- If nothing was missed, reply in writing explaining why, with the facts, and keep a copy.
- Reply before the deadline, or ask in writing for more time.
If you are unsure
This is the moment to get your position reviewed before you reply. A short review now costs far less than a wrong answer to HMRC. We can look at what you have and tell you plainly where you stand.
Common questions
Is a nudge letter the same as an enquiry?
No. An enquiry is a formal process with statutory powers and deadlines. A nudge letter is an invitation to check. It can lead to an enquiry if ignored.
What if I sign the certificate and later find a mistake?
Tell HMRC straight away and make a disclosure. A prompt correction reduces the damage, but it is better not to sign in the first place until you are sure.
Can I ask HMRC what information it holds?
You can ask. HMRC is not obliged to tell you the detail at this stage, but the letter often gives the category. You also have a right to request the personal data HMRC holds about you.
I have already replied saying everything is fine, but it is not.
Write again as soon as possible and make a disclosure. Correcting yourself unprompted is treated far better than being found out.
This page is general information for UK landlords, not advice on your own position. Figures and rules are correct at the review date above and are re-checked after each Budget.