If you’ve received a letter from HMRC referencing “Code of Practice 9” or “CDF”, this is HMRC’s most serious civil tax investigation procedure. The good news: it offers a route out without criminal prosecution. The bad news: you have 60 days to take it and one wrong step closes that door permanently.
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What is Code of Practice 9?
Code of Practice 9 is HMRC’s formal procedure for investigating suspected serious tax fraud by civil means. It is issued by HMRC’s Fraud Investigation Service (FIS) when officers believe there is sufficient evidence that the taxpayer has deliberately understated tax, not just made errors.
Receiving COP9 is not the same as being charged with anything. It is HMRC making a choice: rather than starting a criminal investigation that could end in prosecution, HMRC offers you a civil route to settle, the Contractual Disclosure Facility.
Why HMRC has issued a COP9
COP9 is not issued lightly. HMRC’s Fraud Investigation Service builds a case before sending the letter, drawing on multiple data sources:
- Suspicious Activity Reports (SARs) from banks and accountants
- Common Reporting Standard data from 100+ foreign tax authorities
- Land Registry, deposit scheme and letting agent data (Let Property Campaign)
- UK cryptocurrency exchange data feeds
- Lifestyle and asset-versus-income mismatch analysis
- Whistleblower reports and prior enquiry findings
- Connect, HMRC’s big-data risk engine that cross-references over 30 billion data points
By the time you receive the letter, HMRC typically has more information about your affairs than you might assume. Pretending nothing happened is rarely a viable strategy.
The Contractual Disclosure Facility (CDF)
The CDF is the actual offer embedded inside a COP9 letter. It’s a contract, you accept it formally on an HMRC form. In exchange for accepting:
- You make a full disclosure of all deliberate behaviour that has led to a loss of tax (across every tax head, income tax, corporation tax, VAT, PAYE, capital gains, inheritance tax, etc.)
- You provide an outline disclosure within 60 days, then a comprehensive disclosure report (typically 3–9 months later)
- You cooperate fully throughout
- You pay the tax, interest and a negotiated penalty
In return:
- HMRC guarantees it will not start a criminal investigation into the conduct you disclose
- The penalty range is generally lower than for an uncooperative case
- The matter is settled formally with a written contract closing the disclosed periods
The critical 60-day deadline
The COP9 letter gives you 60 calendar days to respond. By the end of that period you must either:
- Accept the CDF , signing HMRC’s Acceptance Letter and submitting an Outline Disclosure summarising the deliberate behaviour
- Reject the CDF , signing a Denial Letter stating no fraud has occurred
- Fail to respond , treated as rejection and significantly worse than option 2
There is no extension. There is no “I need more time to think.” If the letter arrives while you’re on holiday or out of the country, the clock has still started.
Your three response routes and the consequences
Route 1: Accept the CDF
Appropriate where deliberate tax loss has in fact occurred (even if you didn’t fully understand what you were doing at the time). Properly handled, this is by far the lowest-risk outcome, no criminal record, no public proceedings, a settled civil bill.
Route 2: Deny in writing
Appropriate only where you and your adviser are confident no deliberate behaviour has occurred, perhaps the case is one of carelessness, agent error or HMRC misinterpretation. Filing a denial without basis when fraud has occurred is the worst possible outcome: it removes any prospect of CDF immunity and is taken by HMRC as obstruction.
Route 3: Do nothing
Never advisable. HMRC treats non-response as a denial, but with the added inference of evasion. Criminal referral becomes much more likely.
The COP9 process step by step
- Letter received. 60-day window opens.
- Instruct specialist representation immediately. Most clients shouldn’t rely solely on their general accountant for COP9, the procedural rules are technical and the stakes high.
- Forensic scoping exercise. Your adviser reviews your affairs to determine whether deliberate behaviour has occurred, across which taxes and over what years.
- Decision: accept or deny. Within 60 days.
- Outline Disclosure submitted. A short document setting out the heads of fraud being disclosed.
- Opening meeting. Optional but commonly attended, your adviser handles most of the substantive discussion.
- Disclosure Report prepared. A detailed forensic report covering every relevant year and every tax head, typically 3–9 months of work.
- HMRC review and challenge. Iterative exchanges to settle figures.
- Settlement. Tax + interest + negotiated penalty paid; contract signed; periods closed.
Penalties & tax recovery
The financial exposure under COP9 has three components:
1. Tax
HMRC can recover unpaid tax for up to 20 years where deliberate behaviour is established. For most clients this is the largest single element.
2. Interest
Statutory interest from the date the tax was originally due. With HMRC rates currently elevated, interest on older years can be substantial.
3. Penalty
Calculated as a percentage of the unpaid tax, the penalty depends on three factors:
- Behaviour: careless / deliberate / deliberate-and-concealed
- Disclosure: unprompted (lower) vs prompted (higher)
- Quality of disclosure: the level of help given to HMRC (telling, helping, giving access)
For deliberate behaviour with prompted disclosure (the COP9 default), penalty ranges run from 35% to 70% of the tax. With deliberate-and-concealed conduct, the range is 50% to 100%. Where offshore matters are involved, ranges can rise to 200%.
Most of our work is in this third bucket, reducing the penalty multiplier by getting the behaviour properly categorised and demonstrating maximum cooperation.
Common mistakes that cost clients money
- Trying to handle it alone. COP9 procedure is technical; mistakes are very difficult to unwind.
- Partial disclosure. Disclosing what HMRC already knows but holding back other matters. If discovered, immunity is forfeit and prosecution likely.
- Engaging a general accountant who hasn’t handled COP9. COP9 representation is a specialism. Your existing accountant may be excellent at compliance work and still not the right person for this.
- Voluntary statements to HMRC before instruction. Anything said in an unrepresented meeting becomes evidence.
- Missing the 60-day deadline. No appeal, no extension.
- Underestimating the disclosure scope. The CDF requires disclosure of all deliberate conduct across every tax, not just the matter HMRC referenced in its letter.
How we help COP9 clients
Tax Dispute Consultants is a specialist tax investigation practice. Our team includes former HMRC investigators, we have sat on both sides of the table. For COP9 cases, we:
- Conduct a confidential pre-acceptance review to identify the true scope of disclosure required
- Handle the entirety of HMRC contact, you do not deal with the inspector directly
- Prepare the Outline Disclosure and full Disclosure Report
- Negotiate the penalty categorisation and quality-of-disclosure reductions
- Manage the settlement and contract through to closure