Current position: 1 September 2026. “Nudge letter” is an informal description, not a single statutory document type. The exact wording, stated purpose, enclosed factsheets and any formal notice determine what HMRC has started and what response is required.
A nudge letter is usually a prompt to check and correct
HMRC’s Compliance Handbook describes a “one to many” approach for groups with a similar possible compliance risk where opening a traditional one-to-one check into every recipient may not be justified. The message may highlight a common error, direct recipients to guidance, request a voluntary disclosure or prompt another action.
A nudge letter is not, by itself, a notice that HMRC has opened a formal compliance check. Some current HMRC campaign pages say that failure to respond may lead to further action, including opening a compliance check. That wording distinguishes the present prompt from a possible later check.
A compliance check examines the tax position
A compliance check, sometimes called a tax enquiry, is when HMRC checks a person’s tax position. HMRC says it will call or write to explain what it wants to check and why, and will also contact an authorised tax agent where applicable.
A check may begin with an informal request for information. HMRC may also use statutory information or inspection notices. A failure to comply with a formal information or inspection notice can carry penalty consequences, subject to the legislation and reasonable-excuse rules.
HMRC’s internal enquiry guidance normally requires the relevant CC/FS1 compliance-check factsheet with the opening letter. The presence of a factsheet is a useful cue, but the whole letter and any notice should be read rather than relying on a nickname.
The practical difference is the status and powers being used
| Feature | One-to-many or “nudge” letter | Formal compliance check |
|---|---|---|
| Purpose | Prompt recipients to review a risk, common error or disclosure opportunity. | Check the recipient’s tax position, return, claim, records or calculations. |
| What the letter may say | Check, correct, disclose or explain; it may warn that a check could follow. | HMRC has started or is carrying out a check and identifies the area or reason. |
| Powers | The prompt itself is not automatically a statutory enquiry or information notice. | HMRC may make informal requests or use statutory information and inspection powers. |
| Deadline | Use the date and response route stated in that campaign letter. | Use the opening letter and each formal notice; appeal or penalty rules can be notice-specific. |
A safe reading sequence
- Verify the communication using GOV.UK’s genuine-letter page and a trusted HMRC contact route; do not use contact details from a suspicious message.
- Identify the tax, period, stated concern, requested action and response date.
- Look for wording that says a compliance check or enquiry has opened, the named officer, a CC/FS factsheet, or a statutory information or inspection notice.
- Keep the original letter and a record of the return, records and response used.
- If the status, scope or legal effect is unclear, use HMRC’s published contact route or obtain appropriately qualified help before the stated deadline.
Neither label should be ignored. The distinction prevents a broad campaign prompt from being described as a formal enquiry, while preserving the significance of any real check or statutory notice.
Primary sources
- HMRC Compliance Handbook CH600130 — why HMRC uses a one-to-many approach and the types of prompt; updated 31 July 2026; retrieved 1 September 2026.
- HMRC: check if a letter is genuine — current campaign examples and escalation wording; updated 12 August 2026; retrieved 1 September 2026.
- HMRC compliance checks: help and support — definition, opening contact and process; updated 12 December 2025; retrieved 1 September 2026.
- GOV.UK: tax compliance checks — scope, information notices, outcomes and appeal route; retrieved 1 September 2026.
- HMRC factsheet CC/FS1a — general information about compliance checks; updated 30 April 2025; retrieved 1 September 2026.
- HMRC Compliance Handbook CH207330 — informal requests and statutory information notices; updated 13 August 2026; retrieved 1 September 2026.