
Tax Investigations, Prosecutions & Appeals
HMRC has significant civil and criminal powers to investigate tax irregularities, unpaid tax, offshore issues, tax fraud and tax evasion.
Being investigated by tax and financial authorities can be distressing, disruptive to your personal and professional life, time-consuming and high-stakes. Our experienced team can help defend you from any allegations of financial irregularity and reduce the impact on your life as much as possible.

Strategic defence and resolution for individuals, businesses and advisers
HMRC are becoming more sophisticated in the use of data to assist their risk-profiling of taxpayers. That means there is a greater chance that HMRC will identify those taxpayers who have not paid the correct amount of tax. The level of penalties for making a mistake with your tax affairs can be severe. That makes an early assessment of your position essential.
Our specialist team has experience helping a wide range of individuals and businesses. We will act quickly to protect your position, manage risk and deliver the best available outcome.
We can assist with:
- HMRC enquiries
- Other HMRC disputes and investigations
- Alternative Dispute Resolution
- Complex & International enquiries
- First tier Tax Tribunal / Upper Tribunal
- Criminal investigations and prosecutions
- Code of Practice 8 (COP8) investigations (tax avoidance)
- Code of Practice 9 (COP9) investigations (where HMRC suspects tax fraud)
- Missing Trader Intra-Community (MTIC) fraud investigations (carousel fraud)
- Liechtenstein Disclosure Facility, crown dependency disclosure facilities and other disclosure facilities.

Practical guidance
- Do not ignore deadlines – especially the 60-day COP9 response window
- Keep communications controlled – route everything through your legal team to preserve privilege
- Evidence wins – bank statements, contractual documents, board minutes, valuations and contemporaneous records are critical
- Consider Alternative Dispute Resolution (ADR) early – it can unlock impasses cost-effectively.
Speak to our experts
We have the largest private client team in the UK; our team of experts are here to provide discreet legal advice to support you and your family.

We’re here to help
Complete our enquiry form and one of our experts will contact you by the next working day.
Alternatively, you can call us now.
Our opening hours are Monday to Friday 8am to 6pm (Excluding Public Holidays).
0370 1500 100

Why Irwin Mitchell?
- Specialist team with deep experience in COP8, COP9, high net worth and corporate enquiries.
- End-to-end support: from initial disclosure and HMRC engagement to negotiating settlement agreements, Tribunal litigation, and criminal investigations and prosecutions.
- Integrated expertise across tax, regulatory/criminal, corporate, private client, employment and reputation management.
- Calm, commercially focused advice that balances legal, financial and reputational considerations.
- Discreet and responsive – we move quickly to protect your position from day one.
Making an enquiry
We have several ways you can contact us, either by completing our online contact form, by phone, or using our live chat. If you start your journey online, here are the first steps to working together.
Complete our online formWe need a few details to understand your situation and the kind of support you need.
We’ll contact you by phoneOn the call our experts will ask you a few more questions to make sure we connect you with the right legal advice from our team.
We arrange a full appointmentIf we're able to support you further, the next step is an appointment with one of our specialists so we can discuss everything in more detail.
Frequently Asked Questions
HMRC carries out three main types of tax investigation: a Section 9A enquiry, a Code of Practice 8 (COP8) and Code of Practice 9 (COP9).
These investigations are not criminal investigations and don’t always lead to criminal prosecution. However, HMRC can start criminal investigations and prosecution if you don’t comply or if they find evidence of serious offences.
Section 9A enquiries are used by HMRC to review information entered on your self-assessment tax return. These can relate to a particular aspect of your tax return or a random review of your submission. They are usually conducted through written communication with HMRC.
COP8 investigations are used if HMRC suspects you of tax avoidance or minor fraud. They usually involve a series of informal meetings and correspondence between you and HMRC to identify any underpaid tax.
COP9 investigations are used when HMRC suspects you of serious fraud but hasn’t started a criminal investigation. You must give HMRC a detailed report about your tax affairs, as well as anything you have done that has caused any irregularities, whether deliberate or not.
Once the investigation has settled on a value for any unpaid tax (including interest), you and HMRC negotiate a penalty payment based on your behaviour before and during the investigation. You will pay less of a penalty if you are helpful and cooperative.
Our commitment to you
Our experts always start by listening, so we understand what matters most from day one.- 01Clear legal guidance
You will always get straightforward, honest advice, with regular updates to keep you clear on the way forward.
- 02Specialist knowledge
A wide-ranging team of trusted specialists who understand what it takes to protect your future, your family or your business.
- 03Your needs first
Whether you’re navigating complex personal situations or business decisions, we take the time to understand your world and what’s at stake.




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