The most in-depth and intrusive civil and criminal investigations are carried out by HMRC’s Fraud Investigation Service (FIS). These are not routine compliance checks / enquiries like those carried on by other directorates.
Fraud Investigation Service directorate is part of HMRC’s Customer Compliance Group (CCG), which comprise HMRC’s vast front-line investigative resources. Figures obtained for the 2024/25 year showed that FIS had maintained its officer numbers at around 5,000. CCG numbers stood at around 28,000 in September 2025.
What teams make up HMRC’s Customer Compliance Group?
- Fraud Investigation Service, FIS
- Individuals and Small Business Compliance, ISBC
- Wealthy and Mid-sized Business Compliance, WMBC
- Risk and Intelligence Service, RIS
- Counter Avoidance, CA
- Large Business, LB
Fraud Investigation Service
(SI) Specialist Investigations, which conducted the most serious civil tax investigations like Code of Practice 9 (COP9) and Code of Practice 8 (COP8), and (CI) Criminal Investigations were formally separate directorates, but were combined into the Fraud Investigation Service; established in 2015.
Today, the Fraud Investigation Service is organised into the:
- Prosecutions Unit: Focused on criminal investigations and prosecutions
- UK Tax Matters Unit: Handles domestic tax fraud cases
- Offshore, Corporate, and Wealthy Unit: Deals with complex cases involving offshore assets and high-net-worth individuals
(SPT) Specialist Personal Tax & (PTI) Personal Tax International directorates for example, were moved into WMBC, They comprised technical teams like “Trusts & Estates”, “IHT Compliance”, “Residence, Domicile & Remittance Basis” and “Transfer of Assets Abroad”.
Which tax investigations does Fraud Investigation Service carry out?
HMRC’s Fraud Investigation Service have two distinct “Codes of Practice” under which they civilly investigate what they perceive to be much more serious and/or deliberate tax irregularities.
These are known as Code of Practice 8 (COP8) and Code of Practice 9 (COP9). To be clear, these are distinct from a routine tax investigation / tax enquiry / a compliance check. They are much more intrusive and in-depth, and likely to run on for much longer.
See HMRC’s published guidance on its Criminal Investigation Policy too, to see when they might opt for a COP9 or COP8 investigation instead of a criminal investigation: HMRC’s criminal investigation policy – GOV.UK
At the most serious end of the investigations spectrum, HMRC’s Fraud Investigation Service may commence a criminal investigation with a view to prosecution. They may do this, seemingly out of the blue, or they may changed their approach during an on-going civil tax enquiry or tax investigation. It depends on what they uncover and/or are told.
If you have not yet been approached by HMRC’s Fraud Investigation Service but wish to discuss potentially making a voluntary disclosure (where appropriate), in order to mitigate potential penalties and take control of the whole situation, please visit our tax disclosures page or give us a call on and one of our specialists will discuss the best route for you.
Serious matters are not usually appropriate for regular the regular disclosures route. For example, requesting the COP9 process may be better, to secure immunity from a criminal investigation.
If not a serious FIS tax investigation, then what? Compliance Checks – what powers do HMRC have?
Under the compliance checks / enquiries legislation, HMRC can enquire into your tax affairs by way of a formal ‘compliance check’.
If HMRC commence a compliance check into your personal or business tax/VAT affairs then you should quickly consider whether you feel comfortable dealing with the HMRC enquiry on your own or, as the regular an adviser/agent, or whether you might appreciate specialist and independent tax investigations assistance.
HMRC have the power to request documentation directly from you and also from third parties. Also, they can visit your home and/or business premises and can insist on seeing your records.
It is always in a client’s best interests to explore such matters with a tax disputes specialist if you receive a Notice of tax enquiry from HMRC – even if you have no discrepancies to disclose.
The right help at the right time would ensure that a potentially long, drawn out process is avoided, and effectively managed and concluded. Also, one would ensure that HMRC do not obtain information they were not entitled to, from which they find more risks and raise more questions.
Read more about compliance checks and what Pure Tax Investigations can do to help you or your clients here.
Code of Practice 8 and Code of Practice 9 investigations – what are they?
HMRC’s Fraud Investigation Service use these to investigate what they perceive to be more serious and/or deliberate tax irregularities. Of the two, Code of Practice 9 (COP9) is the more serious, in-depth and intrusive tax investigation. And of course, there is an allegation of suspected tax fraud from the outset.
COP9 is the main civil tax process by which HMRC investigate suspected serious tax fraud. If you or your client receive a COP9 Notification letter, it is extremely important that you consult with a tax disputes specialist as there are very strict time limits which must be adhered to in order to ensure that you/your client are best protected.
Code of Practice 8 (COP8) is the civil HMRC investigation process used by HMRC to investigate suspected tax fraud and/or bespoke tax avoidance and arrangements.
It is important to take any notification from HMRC about proceeding on this basis seriously, as unlike the COP9 process, there is no protection from a criminal tax investigation / prosecution.
Read more about what Pure Tax Investigations can do to help you or your client where a COP8 and COP9 investigation is concerned.
Fraud Investigation Service cases are not routine matters at all.
Criminal Investigations – what can I do?
You or your client might have received a notification from HMRC Fraud Investigation Service that they are commencing a criminal tax investigation. You mat suspect that they are looking to prosecute based on information obtained or your perceived lack of co-operation during a civil enquiry/investigation. We would strongly urge you to get in touch immediately. Specialist tax and legal assistance is very important.
It is imperative that matters are handled carefully and that the right specialists get involved at the right time in order to protect you / the client’s best interests. Also, we would mitigate the likelihood of a successful prosecution and minimise potential reputational damage too.
With the Corporate Criminal Offence for the facilitation of tax evasion by an associate of the business now in effect too, we have seen more criminal prosecutions and much more long-winded tax fraud cases.
Read more about a criminal tax investigation and what Pure Tax Investigations can do to help you or your client facing HMRC here.
HOW CAN PURE TAX HELP?
At Pure Tax Investigations our Tax Investigation, Tax Disclosure and HMRc Disputes Resolution specialists are industry recognised and have dealt with hundreds of contentious situations with HMRC over the years. We are adept at managing interactions with the tax authority to ensure that the investigation and disclosure processes run smoothly and that your interests are best protected.
Remember, Fraud Investigation Service cases are not routine matters, so you should find someone with the appropriate experience and know-how.
