HMRC Compliance, Investigations & Enforcement Guide

1. HMRC Compliance Checks

HMRC can carry out a compliance check to make sure someone is paying the right tax, claiming the right allowances, and receiving the correct reliefs. HMRC may ask for information, documents, explanations, or records.

Official links:
About compliance checks — CC/FS1a
HMRC compliance checks factsheets

2. Tax Investigations

A tax investigation may happen where HMRC believes tax has been underpaid, a return may be wrong, records are incomplete, or fraud may be involved.

HMRC investigations may cover:

• Income Tax
• Self Assessment
• VAT
• PAYE
• Corporation Tax
• Capital Gains Tax
• Tax credits or HMRC-administered payments

For serious suspected fraud, HMRC may use Code of Practice 9, which explains the Contractual Disclosure Facility and the taxpayer’s rights.

Official links:
Code of Practice 9 — where HMRC suspects fraud
Admitting tax fraud using the Contractual Disclosure Facility

3. Record Requests

HMRC may ask for records such as:

• Bank statements
• Invoices
• Receipts
• Payroll records
• VAT records
• Business accounts
• Mileage logs
• Contracts
• Property income records

You should check what HMRC is asking for, the deadline, the tax years involved, and whether the request is informal or formal.

Official links:
About compliance checks — information and documents
Keeping tax records

4. HMRC Powers Explained

HMRC has legal powers granted by Parliament, but those powers are not unlimited.

HMRC may be able to:

• Check tax returns
• Request documents
• Ask questions
• Charge penalties where the law allows
• Charge interest on late tax
• Recover tax debts
• Open civil investigations
• Refer serious cases for criminal investigation

HMRC must still act lawfully, fairly, and proportionately, and follow published guidance and the HMRC Charter.

Official links:
HMRC Charter
Compliance checks factsheets

5. Voluntary Disclosures

If someone discovers they have underpaid tax, they may be able to make a voluntary disclosure to HMRC.

HMRC says people should tell HMRC as soon as they know they owe tax.

Voluntary disclosure can apply to:

• Undeclared income
• Rental income
• Self-employment income
• Offshore income
• Capital gains
• Cryptoasset gains or income

Official links:
Make a voluntary disclosure to HMRC
Tell HMRC about underpaid tax from previous years
Worldwide Disclosure Facility
Let Property Campaign
Tell HMRC about unpaid tax on cryptoassets

6. Mistakes vs Tax Fraud

Not every error is fraud.

HMRC commonly distinguishes between:

Reasonable care

A genuine mistake may happen even where someone took reasonable care.

Careless behaviour

A careless error can happen where someone failed to take reasonable care.

Deliberate behaviour

Deliberate behaviour means the person knew the return or document was wrong.

Deliberate and concealed

This is more serious and may involve hiding the error.

HMRC’s penalty guidance says penalties may depend on whether an inaccuracy was careless, deliberate, or deliberate and concealed.

Official links:
Penalties for inaccuracies — CC/FS7A
Reasonable care — HMRC Compliance Handbook

7. Responding to HMRC Letters

When you receive an HMRC compliance letter:

1. Check it is genuine.
2. Read the deadline carefully.
3. Identify what tax years and taxes are involved.
4. Gather records before replying.
5. Do not guess if you are unsure.
6. Ask HMRC for clarification where needed.
7. Seek professional advice if fraud, penalties, large debts, or complex issues are involved.
8. Keep copies of everything sent and received.

Official links:
Check if a letter from HMRC is genuine
HMRC contact information

8. Penalties & Fines

HMRC may charge penalties for:

• Late filing
• Late payment
• Inaccurate returns
• Failure to notify HMRC
• Failure to keep records
• Deliberate under-declaration
• Concealment

For some inaccuracies, HMRC penalty ranges depend on behaviour, disclosure, and cooperation. HMRC’s guidance says penalties can be reduced depending on disclosure quality.

Official links:
Self Assessment penalties
Penalties for inaccuracies — CC/FS7A
Penalties for failure to notify — CC/FS11

9. Human Rights and HMRC Penalties

Where HMRC is considering certain penalties, Article 6 rights under the European Convention on Human Rights may apply. HMRC has a factsheet explaining these rights in penalty cases.

Official link:
Human Rights Act and penalties — CC/FS9

10. If You Disagree With HMRC

You may be able to:

• Ask HMRC for an explanation
• Send further evidence
• Ask for a review
• Appeal to a tax tribunal
• Make a complaint about service

Official links:
Appeal a tax decision
Complain about HMRC
HM Courts & Tribunals Service

11. Data Protection and Privacy Rights

HMRC must follow UK data protection law when handling personal information.

You may have rights to:

• Request personal information HMRC holds
• Ask for inaccurate information to be corrected
• Complain about misuse of personal data
• Contact the Information Commissioner’s Office

Official links:
HMRC Subject Access Request
Information Commissioner’s Office
Data Protection Act 2018

12. Trusted Help and Advice

Official and independent sources:

HMRC compliance checks factsheets
TaxAid
Low Incomes Tax Reform Group
Citizens Advice
MoneyHelper

Key Principle

HMRC has legal powers to check tax, request records, charge penalties, recover tax, and investigate suspected fraud. Taxpayers also have rights to fair treatment, clear explanations, privacy, representation, review, appeal, and protection under human rights and data protection law. Always respond to HMRC letters on time, keep records, avoid guessing, and seek qualified advice where fraud, large penalties, or complex investigations are involved.