A brown envelope marked "Code of Practice 9" is among the most consequential letters HMRC ever sends. It signals that the agency suspects deliberate behaviour involving tax — fraud, in plain English — and is offering the taxpayer a structured route to confess, disclose, and settle without criminal prosecution. The framework around it, the Contractual Disclosure Facility (CDF), is a once-in-a-lifetime opportunity, and missteps in the first 60 days can be irreversible.
What COP9 is, and is not
Code of Practice 9 is HMRC's published policy for civil investigations where deliberate behaviour is suspected. It is not, on its face, a criminal proceeding — but it sits alongside the Crown Prosecution Service's separate criminal track, and the choice between civil and criminal routes is HMRC's, not the taxpayer's. Acceptance of the CDF guarantees that HMRC will not pursue criminal prosecution for the matters disclosed, provided the disclosure is complete and accurate.
The 60-day decision
When COP9 is issued, the taxpayer has 60 days to either accept or reject the CDF offer. There is no third option to ignore.
- Accepting the CDF commits the taxpayer to making a complete disclosure of all deliberate tax irregularities, providing supporting documents, and cooperating fully throughout the investigation.
- Rejecting the CDF (or failing to respond) leaves HMRC free to pursue either civil investigation under any code, or to refer the matter for criminal prosecution. There is no protection against either route.
- Denying any deliberate behaviour while engaging with the investigation is a separate option, but it forfeits the criminal protection of the CDF — if HMRC subsequently proves deliberate behaviour, criminal prosecution remains live.
The outline disclosure
Within the 60-day window, accepting taxpayers must submit an "outline disclosure" describing the broad nature of the irregularities, the taxes affected, the periods involved, and an initial estimate of unpaid tax. This is not the full disclosure — that comes later — but it must be sufficient to identify the issue and demonstrate cooperation. An outline disclosure that minimises or omits issues that emerge later can void the CDF protection.
The full disclosure report
After the outline is accepted, the taxpayer (working with their adviser) prepares a detailed disclosure report covering every irregularity, the mechanism, the amounts, the periods, the persons involved, and the supporting documentation. This typically takes several months and involves forensic reconstruction of bank accounts, business records, and personal expenditure. The report becomes the basis for settlement.
Settlement: tax, interest, and penalties
COP9 settlements involve three components:
- Tax for all years in which deliberate behaviour applied — up to 20 years under the extended assessment provisions of TMA 1970 s.36.
- Interest from the original due dates of each tax liability, compounding over the disclosure period.
- Penalties under Schedule 24 Finance Act 2007 (and equivalents for other regimes), which for deliberate behaviour start at 35% of the tax and can rise to 100% (or 200% for offshore matters). Cooperation and disclosure quality reduce the penalty within the prescribed range.
The penalty range is critical: a deliberate but unprompted disclosure with full cooperation can settle near the bottom of the band, whereas a deliberate, prompted, concealed disclosure sits at the top.
Working with a specialist
COP9 cases are not routine tax work and most general accountants will refer to a specialist tax investigations practice or specialist counsel. The investigator at HMRC's Fraud Investigation Service (FIS) has often been working the case for months before the COP9 letter is issued, and may already hold third-party information from banks, foreign authorities, or whistleblowers. Walking in unprepared is dangerous.
What COP9 is not
COP9 is reserved for deliberate behaviour. If an irregularity arose from carelessness rather than deliberation, the matter should not be in COP9 at all — it would normally proceed under Code of Practice 8 or as a routine enquiry. Conversely, COP9 does not cover purely criminal offences such as VAT carousel fraud, where the criminal track is generally taken from the outset.
If you receive a COP9 letter
- Do not respond immediately. Read the letter carefully and engage a specialist within days, not weeks.
- Do not destroy documents. Document destruction after a COP9 letter can itself be an offence.
- Do not discuss the case widely. Confidentiality protects both you and any related parties.
- Take stock honestly. The CDF only works if disclosure is genuinely complete; partial disclosure loses the protection without resolving the problem.
This article is general information and not advice on any specific COP9 case. If a COP9 letter has been received, professional advice should be sought immediately. Our business advisory team works alongside specialist tax investigation counsel where appropriate, and the earlier we engage, the more constructive the eventual settlement tends to be. Reach us via the contact page or book a confidential call.