An HMRC investigation letter is not something to ignore or handle alone. Whether it's a routine check or a full investigation, how you respond in the early stages can significantly affect the outcome.
HMRC conducts different types of checks: an 'aspect inquiry' looks at one part of your tax return; a 'full inquiry' examines everything. They may also conduct a Code of Practice 9 investigation for suspected serious fraud. The letter will tell you what type of inquiry it is. HMRC has wide powers: they can request bank records, interview you under caution, and investigate going back up to 20 years in cases of deliberate non-compliance. Cooperating promptly and accurately is important, but so is understanding what you're required to provide and what rights you have.
Is it a routine check, an aspect inquiry, or a full investigation? The letter should make this clear. A simple query about one line of your tax return is very different from a formal investigation.
Even if the inquiry seems small, speak to your accountant or a tax adviser before submitting anything to HMRC. Anything you say or provide can form part of their case.
HMRC will want documentation. Start collecting bank statements, receipts, invoices, contracts, and any records relevant to the period under investigation.
HMRC deadlines must be taken seriously. If you need more time to gather documents or take advice, call them and ask for an extension before the deadline — they often grant reasonable requests.
For anything beyond a simple query, a specialist tax investigation accountant or solicitor is worth the cost. They negotiate with HMRC on your behalf and know what to disclose and what to challenge.
Describe exactly what happened and the AI will give you personalised next steps — free.
HMRC uses data-matching technology to flag anomalies. Triggers include: large or unusual income changes, discrepancies between income and lifestyle, missed payments, or tips from third parties. Being investigated doesn't automatically mean you've done anything wrong.
For honest errors, you'll owe the unpaid tax plus interest and possibly a penalty (reduced if you cooperate). For deliberate evasion, penalties are much higher and criminal prosecution is possible.
Yes. HMRC can request bank statements from your bank directly without your permission in formal investigations. They can also access information from third parties including employers and overseas authorities.
A simple aspect inquiry might be resolved in a few months. A full investigation can take 1-3 years. Cases involving serious fraud can take even longer.
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