What is a COP9 investigation?

If you have received a letter from HM Revenue & Customs (HMRC) saying you are under a COP9 investigation, do not ignore it!

COP9 – short for Code of Practice 9 – is one of the most serious types of HMRC tax investigation.

It is launched when HMRC suspects that you have deliberately underpaid tax or committed tax fraud.

Under COP9, HMRC gives you a chance to make a full disclosure of all irregularities in your tax affairs through the Contractual Disclosure Facility (CDF).

In return, HMRC promises not to carry out a criminal investigation, provided you are honest and complete in your disclosure.

Should I be worried about a COP9 investigation?

Yes – you should take it seriously.

COP9 is not the same as a routine tax check.

It means HMRC already suspects tax fraud involving substantial amounts.

Refusing to cooperate with a COP9 investigation or providing an incomplete disclosure can lead to severe penalties, criminal prosecution, and reputational damage.

What triggers a COP9 investigation?

HMRC can open a COP9 investigation for various reasons, but all involve a suspicion of tax fraud, for example:

• Unreported sources of income or gains
• Undeclared offshore income or assets
• Failure to file self-assessment returns or company accounts
• Misappropriating company income
• Inaccurate VAT repayment claims

If HMRC has started a COP9 investigation, they already have some key information. This could be through international tax agreements or from whistleblowers.

What should I do if I receive a COP9 letter?

If you receive a COP9 notice, you have 60 days to decide whether to accept HMRC’s offer to use the Contractual Disclosure Facility. Your options are:

• Accept and make an outline disclosure of all deliberate and non-deliberate errors in your tax affairs
• Reject, in which case HMRC may escalate the matter to a criminal investigation

It is essential to seek specialist advice immediately before responding.

An experienced tax adviser can help you assess your position, prepare your disclosure, and minimise penalties.

Can I appeal a COP9 investigation?

You cannot “appeal” against HMRC’s decision to open a COP9 investigation – it is not a penalty or tax assessment.

However, you can dispute HMRC’s suspicions during the process if you believe their information, or understanding of it, is wrong.

You can appeal against any tax assessments or penalties that result from the investigation, but there are strict time-limits for appealing.

This is why having expert representation is critical from the outset.

What are the penalties for COP9?

HMRC charges penalties as a percentage of any undeclared tax that has been identified. The penalty rate depends on the behaviour and your co‑operation throughout the investigation.

If HMRC starts a COP9 investigation, the minimum penalty rate for deliberate behaviour is 35 per cent. The penalty rate is higher if HMRC identifies ‘concealment’, adequate cooperate has not been provided, or there is an offshore element to the additional tax.

How long does a COP9 investigation take?

COP9 cases are complex and can take 18 months or more to conclude.

The exact timeframe depends on the scope of the disclosure, the number of years HMRC involved in the investigation, and whether you co‑operate fully.

The advice from inTAX

A COP9 investigation is HMRC’s most powerful tool to tackle tax fraud outside of a criminal investigation.

Opening that brown envelope from HMRC and discovering a COP9 letter inside is a deeply unsettling moment.

The CDF gives you a valuable opportunity to resolve matters and the protection from criminal charges.

If you have received a COP9 letter – or think one may be on the way – the most important step you can take is to get expert help immediately.

Early, honest, and thorough action can make all the difference to the outcome.

You can speak to our friendly and experienced team on: 0203 675 8122 or email jeremy.johnson@intaxltd.com directly.

inTAX is a specialist tax disputes firm. We deal with disclosures, investigations, and tax enquiries of all descriptions, including COP9, fraud investigations, VAT fraud, tax avoidance, let property disclosures and tribunal appeals. However, we don’t just deal with the serious end of tax investigations; we are also happy to handle smaller enquiries, disputes and problems that can be equally as worrying for our clients