posted 9th December 2025
The Difference Between COP6 and COP9 – And How a Case Can Move from One to the Other
HMRC uses several different investigation routes depending on what it believes has gone wrong in a taxpayer’s affairs. Two of the most misunderstood are Code of Practice 6 (COP6) and Code of Practice 9 (COP9).
Although both relate to suspected irregularities, they are very different in seriousness, purpose, and the risks involved. In some cases, a COP6 enquiry can escalate into COP9, or HMRC may begin with COP9 if it believes tax fraud has taken place.
Understanding these differences is essential because how you respond in the early stages can shape the entire outcome of the investigation.
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What Is COP6?
COP6 is HMRC’s standard civil investigation where they suspect errors, omissions, or irregularities, but not deliberate fraud. A COP6 investigation typically involves:
- Requests for detailed financial records
- Examination of tax returns across multiple years
- Questions about specific transactions or patterns
- Interviews or written explanations
The key point is that HMRC is not accusing the taxpayer of deliberate wrongdoing at this stage. They are investigating the possibility of:
- Careless errors
- Mistakes caused by poor record-keeping
- Incorrect interpretation of tax rules
- Incomplete disclosure
While COP6 is serious, it remains within the civil enquiry framework. It can lead to adjustments, penalties, and interest — but normally not criminal prosecution, unless new evidence emerges.
What Is COP9?
COP9 is reserved for the most serious civil fraud cases. It is used when HMRC believes there has been deliberate tax evasion, not simply carelessness. COP9 is offered under the Contractual Disclosure Facility (CDF). This gives the taxpayer a choice:
- Admit deliberate tax fraud and make a full disclosure
- Deny the allegation — risking criminal investigation
Under COP9, HMRC offers a powerful incentive:
If the taxpayer fully cooperates and discloses all deliberate irregularities, HMRC will not pursue criminal prosecution. The COP9 process involves:
- A formal, legally binding disclosure
- A detailed outline of deliberate behaviour
- A full report covering all years of irregularities
- Forensic review of financial affairs
- Strict penalties (but usually lower than in criminal cases)
COP9 is extremely serious and should never be handled without expert representation.
Key Differences Between COP6 and COP9
COP6 = HMRC wants clarity.
COP9 = HMRC believes fraud has taken place.
| Feature | COP6 | COP9 | |
|---|---|---|---|
| Suspicion Level | Errors or carelessness | Deliberate tax fraud | |
| Criminal Risk | Low (unless escalated) | Avoid criminal prosecution only with full disclosure | |
| Disclosure Requirement | Provide records & explanations | Full admission of deliberate behaviour required | |
| Penalty Range | Typically lower | Can be significant, but reduced if fully cooperative | |
| Approach | Investigative | Forensic & legal | |
| Tone | Neutral | Highly formal and serious | |
| Duration | Months to 1 year | Often 1–2+ years |
How a Case Can Move From COP6 to COP9
It is entirely possible, and not uncommon, for a COP6 enquiry to escalate into COP9. HMRC may start under COP6 because they only suspect errors, but if during the enquiry they uncover evidence suggesting deliberate behaviour, the case can be reclassified.
This escalation may occur if:
1. Undeclared Income Is Found: For example, rental income, cash takings, online sales, or side-business income not previously disclosed.
2. Records Appear Manipulated: Gaps, alterations, and inconsistent explanations can lead HMRC to suspect intent.
3. Discrepancies Cannot Be Explained: If HMRC believes the taxpayer is withholding information or giving misleading statements.
4. Bank Analysis Reveals Concealment: Personal and business accounts showing unexplained deposits or overseas transfers often prompt escalation.
5. Behavioural Signs Suggest Deliberate Action: Such as:
- Repeating the same “errors” every year
- Artificially reducing tax
- Destroying or failing to provide records
When HMRC’s internal fraud indicators are triggered, the enquiry is typically withdrawn and replaced with a formal COP9 CDF offer. When that happens, everything changes: The taxpayer moves from a relatively manageable civil enquiry to a high-stakes disclosure process with potential criminal implications.
Can a Case Ever Move From COP9 Back to COP6?
This is far less common, but it can happen. Occasionally HMRC discovers that an issue originally believed to be deliberate was actually:
- A misunderstanding
- A bookkeeping error
- A technical tax point
- A professional mistake by an accountant
In such cases, HMRC may withdraw COP9 and continue under COP6 or close the case entirely. However, this outcome usually only happens when the taxpayer has strong representation, clear evidence, and a well-managed response strategy.
Why Expert Help Is Essential
The biggest risk in both COP6 and COP9 is saying or submitting the wrong thing. Even an innocent comment during a COP6 enquiry can lead HMRC to escalate the case. With COP9, the risk is even greater: the taxpayer is entering a legally binding process where every word matters. Specialist guidance ensures:
- Correct interpretation of HMRC’s position
- Protection from self-incrimination
- Proper management of disclosure obligations
- Reduction of penalties
- Prevention of escalation
Whether you’re facing a COP6 enquiry or have received a COP9 CDF letter, you must act carefully. At Tax Investigation Helpline, our independent experts specialise in HMRC investigations, disclosure processes, and defence strategies.
We help you understand your position, protect your rights, and achieve the best possible outcome, while keeping the situation under control. Contact us today for confidential, expert advice before speaking to HMRC.
