Code of Practice 9 is the procedure HMRC uses when it suspects serious tax fraud and chooses, for now, to investigate it through a civil route. The letter comes with an offer: a Contractual Disclosure Facility (CDF) contract. You have 60 calendar days from receiving the letter to accept or reject that offer, under HMRC's published CDF guidance. Accepting means admitting that deliberate behaviour on your part brought about a loss of tax, and committing to a full disclosure. It is a decision with lasting consequences, and the response should be planned, not improvised. HMRC's published Code of Practice 9 sets out the process, and our COP9 and Code of Practice 9 service page explains how we handle these cases. Correct as at 11 August 2026.
What is a COP9 investigation (Code of Practice 9)?
A COP9 letter means HMRC suspects tax fraud and has decided to offer you a civil route to resolve it. The letter typically says little about what HMRC believes it has found; the substance surfaces later, through the disclosure process.
Under the CDF, HMRC's guidance gives you two options: own up to bringing about a loss of tax through deliberate behaviour, by accepting the offer, or reject it. Doing nothing does not park the matter. Once the 60 days pass without acceptance, the protection on offer lapses and HMRC continues its investigation on its own terms.
What does accepting the CDF involve?
Accepting is an admission that your deliberate behaviour brought about a loss of tax, duty or a payment administered by HMRC. In return, HMRC agrees not to open a criminal investigation with a view to prosecution for the deliberate conduct you disclose under the contract. HMRC's guidance is explicit that accepting the offer and making a full disclosure is the only way to be certain of that outcome.
Acceptance involves completing HMRC's Outline Disclosure form: a first, structured account of what you did, how, and over what period. Most cases then move to a detailed disclosure report prepared with your adviser, supported by records and, where needed, meetings with HMRC.
You can authorise an adviser to deal with HMRC for you using form COMP1, and the same guidance covers making payments on account of the tax as the figures firm up. Both are practical signals that the process is designed to be worked through with professional support, not alone.
What does the Outline Disclosure actually contain?
The Outline Disclosure form is not the full account of the fraud; it is the formal admission plus a structured description of what happened. HMRC's guidance points to the completion instructions built into the form itself (parts 4 and 4a), and provides a route to ask its COP9 team questions about completing it. Broadly, it needs to identify each area of deliberate conduct you are admitting, how it was carried out, the entities and accounts involved, and the periods it covers.
Its quality matters more than any other document in the process. Conduct left out of the outline is conduct outside the contract's protection, and an outline drawn too vaguely invites HMRC to treat the disclosure as incomplete. Equally, it is an admission document: nothing belongs in it that has not been established by a proper review. This is why the 60 days are spent on a privileged fact-finding exercise first and drafting second.
Two practical tools sit alongside it in the guidance. Form COMP1 authorises HMRC to deal with your adviser directly, so the channel runs through one professional. And the payment on account section exists because starting to pay early, once figures begin to firm up, reduces the interest accruing and evidences the cooperation HMRC says it considers when penalties are worked out.
What if you reject the offer, or did nothing wrong?
Rejecting the CDF is the right course where there is no deliberate conduct to admit. It needs the same care as acceptance: HMRC does not drop the matter because the offer is declined. It continues to investigate, and where it still suspects fraud, a criminal investigation becomes possible.
If the true position is error rather than fraud (a careless mistake, a misunderstood rule), that explanation, evidenced properly, belongs in your response. What you should not do is accept the contract to make the letter go away. Admitting deliberate conduct that did not occur creates serious problems of its own. The accept-or-reject decision is exactly where specialist advice earns its keep.
The three routes compared
| Route | What it means | Where it leads |
|---|---|---|
| Accept the CDF | Admit that deliberate behaviour brought about a tax loss; complete the Outline Disclosure; cooperate fully | HMRC agrees not to criminally investigate the disclosed conduct with a view to prosecution; the case resolves civilly, with tax, interest and penalties |
| Reject the offer | A formal denial that deliberate conduct occurred | HMRC continues investigating, civilly or criminally; the CDF protection is off the table |
| Let the 60 days lapse | No response | Treated no better than rejection; HMRC proceeds on its own terms, without your side on record |
Can you come forward before HMRC writes?
Yes. The same guidance covers voluntarily admitting tax fraud: you can approach HMRC and ask for a CDF contract before any letter arrives. HMRC states that how you cooperated in meeting the terms of the contract is considered when penalties are worked out, and coming forward before HMRC finds you is materially different from being found. Data from banks, letting platforms, crypto exchanges and overseas tax authorities reaches HMRC routinely, so where deliberate conduct exists, discovery is often a matter of time.
If what you received is a prompt rather than a COP9 letter, that earlier stage works differently: our guide to HMRC nudge letters covers it.
Example
Example. A company director receives a COP9 letter on a Tuesday. That week, with an adviser, she diarises the 60-day deadline and starts a privileged review of her personal and company tax position. The review finds two things: a rental profit understated through a bookkeeping error, and offshore investment income that was deliberately left off returns over several years. The first, on its own, would point to rejecting the offer and evidencing the error. The second cannot be explained as a mistake, so the advice is to accept the CDF, complete the Outline Disclosure covering the deliberate conduct, and prepare the detailed disclosure with payments on account as the figures firm up. Had the review found only the bookkeeping error, the right response would have been the opposite one.
What to do now
Note the date the letter arrived and count the 60 days forward. Gather your personal and business records, including anything offshore. Say nothing substantive to HMRC before taking advice, and do not sign anything to buy time. Then take specialist advice in week one, not week seven: the quality of the Outline Disclosure shapes everything that follows.
Our Code of Practice 9 page explains how we run these cases, and our tax investigations team handles the wider enquiry spectrum.
Frequently Asked Questions
No. COP9 is a civil procedure, but it exists because HMRC suspects serious fraud, and the criminal route stays available if the offer is rejected or the disclosure falls short. HMRC agrees not to criminally investigate the conduct you disclose only where the CDF contract is accepted and honoured.
The offer lapses and HMRC continues its investigation without the CDF's protection. Not responding leaves you in the same position as rejection, without the benefit of having put your side on record. Diarise the deadline on day one.
No. The CDF is an admission of deliberate conduct, and accepting it to make the letter go away creates serious problems of its own. If the position is error rather than fraud, the offer can be rejected and the explanation evidenced. Take advice before responding either way.
Yes. HMRC's guidance covers voluntarily admitting tax fraud and asking for a CDF contract before any investigation starts. Cooperation is expressly considered when penalties are worked out, so coming forward first is a stronger position than being found.
Not directly, and not informally. Anything said to HMRC during the 60 days is part of the record, and an unguarded phone call can prejudice both the accept and reject routes. The safer sequence is advice first, then a single authorised channel to HMRC through your adviser using form COMP1.
No. Acceptance settles the route, not the figures. The tax, interest and penalties are established through the disclosure process that follows, tested against records, and paid at the end or through payments on account along the way. Expect that phase to be measured in months, driven by how complex the affairs are.
Talk to us before you respond
If a COP9 letter has arrived, speak to Ghulam Alahi, Managing Director, who has more than 25 years' experience in HMRC enquiry and COP9 work, before anything goes back to HMRC. The first conversation covers what the letter does and does not tell you, how the 60 days will be used, and who should deal with HMRC from here. Call 020 8554 2135 or email info@visionconsulting.co.uk, or use our contact page.
By the Vision Consulting team.
This is general information, not advice. Your position depends on your circumstances.