HMRC Compliance Checks: Complete Support Guide (2026)
A brown envelope from HMRC announcing a “compliance check” is unsettling, but it doesn’t automatically mean HMRC suspects wrongdoing. Compliance checks are how HMRC tests the accuracy of what’s been reported across VAT, PAYE, Corporation Tax, and Self Assessment u2014 and in the 2023/24 tax year alone, this activity protected or collected £41.8 billion for the Exchequer. This guide from Filing Accounts UK explains how compliance checks work across every major tax type, what to expect, and how to prepare, using only verified facts from official HMRC guidance.
At Filing Accounts, we support clients through HMRC compliance checks across VAT, PAYE, Corporation Tax, and Self Assessment. If you’re specifically facing a Self Assessment check, see our detailed guide on what happens during a Self Assessment enquiry.
What Is an HMRC Compliance Check?
A compliance check is a formal review of your tax records and returns, checking they’re accurate and complete. HMRC selects cases using a combination of risk-based profiling (data-matching against third-party sources, unusual patterns, industry benchmarks), random selection, and sometimes a specific tip-off or discrepancy. Being selected doesn’t mean HMRC has already concluded something is wrong u2014 many checks close with no changes at all.
The Three Types of Check
- Aspect check u2014 focused on one specific area, such as a single VAT return or a particular expense category
- Full check u2014 a comprehensive review of all your tax affairs across the relevant records
- Random check u2014 selected with no specific trigger, simply to test overall compliance levels
VAT Compliance Checks
Any VAT-registered business can be selected u2014 sole traders, contractors, small companies, and large firms alike. HMRC checks that sales, purchases, and VAT owed have been reported correctly, and checks can be triggered by routine sampling or by figures that look unusual against expected patterns for your business.
Typical evidence requested includes VAT workings, sales and purchase invoices, and bank statements reconciled against your returns. Checks generally must be opened within the standard 4-year assessment window, extending to 20 years in cases of deliberate under-declaration. If you’re behind on VAT payments as well as facing a check, see our guide on what to do if you can’t pay your VAT bill.
PAYE and Employer Compliance Checks
These focus on whether an employer has operated PAYE correctly u2014 covering payroll records, RTI submissions, benefits in kind reported via P11D, National Insurance, and worker status. A common trigger area is employment status u2014 whether people treated as self-employed contractors should genuinely have been on payroll, an issue closely tied to IR35 for businesses using contractors. Expect HMRC to request payroll reports, contracts, and evidence supporting how worker status decisions were made.
Corporation Tax Compliance Checks
HMRC generally has 12 months from your CT600 filing date to open a standard check into a Corporation Tax return. Common areas of focus include the accuracy of expense claims, correct application of marginal relief, and director’s loan account treatment u2014 see our guide on common CT600 mistakes that trigger an enquiry for the specific errors HMRC tends to flag.
Self Assessment Compliance Checks
HMRC generally opens a check within 12 months of when you filed, if filed on time. This is the most detailed area to cover, and we have a dedicated guide walking through aspect checks, full checks, discovery assessments, time limits, and penalties: What Happens If HMRC Opens a Self Assessment Enquiry?
What Happens During a Check: Step by Step
1. Scope and Period Confirmed
HMRC’s opening letter sets out which tax (VAT, PAYE, Corporation Tax, or Self Assessment) and which periods are under review.
2. Information Request
You may be asked for invoices, bank statements, contracts, payroll reports, VAT workings, or management accounts, typically with 40 days to respond from the date of the request.
3. Clarification Call or Meeting
HMRC may want to understand your business model, systems, and controls in more depth, particularly for a full check.
4. Outcome Letter
HMRC either closes the check with no changes, requests adjustments, or proposes penalties where it believes there’s an inaccuracy.
5. Appeal or Review
If you disagree with the outcome, you can request an internal HMRC review, or appeal to the independent tax tribunal.
How Long Checks Take
| Check Type | Typical Duration |
|---|---|
| Aspect check | 3 to 6 months |
| Full check | 9 to 18 months, depending on complexity |
What If You Don’t Provide Information in Time?
Missing the deadline on a formal information notice can result in a penalty of up to £300, with a further £60 per day for continued non-compliance. This is separate from any penalty relating to the accuracy of the return itself u2014 responding on time, even to request an extension, is always better than letting a deadline pass silently.
Making Tax Digital Is Changing How Checks Work
MTD for VAT has been mandatory since 2022, and MTD for Income Tax became mandatory from April 2026 for sole traders and landlords above the qualifying threshold. Both create a continuous digital record HMRC can review directly, which changes the nature of compliance checks over time u2014 businesses using MTD-compatible software with clean digital records generally experience a smoother, faster check than those relying on manual or paper-based bookkeeping.
How to Prepare
- Keep invoices, receipts, bank statements, and payment records organised and easy to retrieve, not just filed away
- Review your own returns before HMRC does u2014 spotting and voluntarily correcting an error yourself generally leads to a lower penalty than HMRC finding it independently
- Respond to information requests within the stated timescale, or ask for an extension before the deadline passes, not after
- Get professional representation early u2014 many advisers can act as your agent, managing correspondence and attending calls on your behalf
HMRC Compliance Checks at a Glance
| Tax Type | Standard Check Window |
|---|---|
| Self Assessment | 12 months from filing (if on time) |
| Corporation Tax | 12 months from CT600 filing date |
| VAT | 4 years standard, up to 20 years for deliberate errors |
| PAYE | No fixed single window — risk-based and ongoing |
Common Mistakes to Avoid
Assuming a Check Means You’re Under Suspicion
Random and routine checks make up a real proportion of HMRC’s activity u2014 many close with no changes at all.
Ignoring the Information Notice Deadline
Missing the 40-day window triggers its own penalty, separate from anything relating to the underlying tax return.
Handling Multiple Tax Types as Separate, Unrelated Issues
A PAYE worker-status issue can have knock-on VAT and Corporation Tax implications, and vice versa u2014 a joined-up response across all affected taxes is usually stronger than addressing each in isolation.
Frequently Asked Questions
Does a compliance check mean HMRC thinks I’ve done something wrong?
Not necessarily. Checks include random selection alongside risk-based and data-matching triggers, and many close with no changes required.
How long does an HMRC compliance check take?
An aspect check typically takes 3 to 6 months; a full check can take 9 to 18 months depending on complexity.
Can I be checked on more than one tax at once?
Yes. HMRC runs checks across Self Assessment, VAT, PAYE, and Corporation Tax, and issues in one area can prompt a look at related taxes.
What happens if I miss an information request deadline?
A penalty of up to £300 can apply, plus £60 a day for continued non-compliance, separate from any penalty relating to the tax return itself.
Can I have someone represent me during a check?
Yes. An accountant or tax adviser can act as your agent, handling correspondence and attending calls or meetings on your behalf.
Facing an HMRC Compliance Check? Talk to Filing Accounts UK
Whatever tax the check covers, having an experienced adviser manage the correspondence and evidence from the outset makes a real difference to the outcome. At Filing Accounts, we support clients through VAT, PAYE, Corporation Tax, and Self Assessment compliance checks, from the first letter through to resolution.
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