When HMRC opens a tax investigation, many people wonder what information it already holds.
Has HMRC seen a bank transaction? Did a customer provide information? Has an overseas bank reported an account? Or has an unusual figure on a tax return simply raised a question?
HMRC may not explain the full reason for an investigation at the beginning. Instead, it normally identifies the tax, period or transaction it wants to check and asks the taxpayer for relevant information.
The evidence HMRC uses will depend on the case. However, most investigations involve comparison: HMRC looks at what the taxpayer declared and compares it with records from other sources.
Tax Returns and Information Already Held by HMRC
The starting point is often information that the taxpayer or their employer has already submitted.
This may include:
- Self Assessment tax returns;
- company tax returns and accounts;
- VAT returns;
- PAYE and payroll submissions;
- Construction Industry Scheme records;
- capital gains disclosures; and
- earlier correspondence with HMRC.
HMRC can compare information across different taxes and years. For example, figures in a company’s accounts may not appear consistent with its VAT returns. A director’s personal tax return may also show income that differs from the company’s payroll or dividend records.
An inconsistency does not automatically prove that somebody has underpaid tax. Different taxes follow different rules, and timing differences are common. However, an unexplained difference may lead HMRC to ask further questions.
If you want to understand the general process first, our guide to what happens during an HMRC enquiry explains how a compliance check may progress.
Bank and Building Society Records
Bank statements often play an important role in tax investigations.
HMRC may ask a taxpayer to provide statements for business accounts. In some cases, it may also ask about personal accounts where they are relevant to the tax position—for example, when business income may have entered a personal account.
Investigators may review:
- unexplained credits;
- transfers between accounts;
- cash deposits;
- payments from customers;
- overseas transfers;
- personal expenditure paid by a business; and
- transactions that do not match the accounting records.
A credit on a bank statement does not always represent taxable income. It could be a transfer between accounts, a loan, an inheritance, a repayment or the return of capital. Nevertheless, the taxpayer may need evidence to explain it.
HMRC does not have unrestricted access to every bank account whenever it wishes. However, it can use statutory information powers in appropriate circumstances and may obtain relevant information from third parties.
Our article Can HMRC Check Your Bank Account? explains the distinction between HMRC’s information-gathering powers and the idea that it can simply browse private accounts at will.
Business Books and Accounting Records
For businesses, HMRC may examine the records used to prepare tax returns and accounts.
These can include:
- sales and purchase invoices;
- receipts;
- bookkeeping records;
- accounting software;
- till records;
- stock records;
- expense claims;
- mileage logs;
- payroll files;
- contracts; and
- correspondence relating to transactions.
HMRC will often check whether the records support the figures submitted. It may also test whether the records appear complete.
For example, an investigator might compare daily till totals with cash deposits, card receipts and declared sales. Alternatively, HMRC may compare purchase volumes with reported turnover to assess whether the sales figure appears reasonable.
Poor records do not automatically prove deliberate tax evasion. However, gaps can make it harder for a taxpayer to demonstrate that a return was correct.
Information from Employers, Customers and Other Third Parties
HMRC does not have to rely only on documents supplied by the person under investigation.
It may already hold information from employers, pension providers, financial institutions and other organisations. Depending on the case and the relevant legal powers, HMRC may also request information from a third party.
Examples may include:
- employment and pension income;
- interest reported by financial institutions;
- records held by payment processors;
- details from property transactions;
- information from contractors or customers;
- records held by online platforms; and
- documents from connected businesses.
Third-party information can reveal a difference, but it still needs context. A customer’s records may contain an error, describe the transaction incorrectly or record it in a different accounting period.
Therefore, taxpayers should not assume that information held by HMRC must be correct. Instead, they should compare it with their own records and explain any genuine difference with evidence.
Overseas Financial Information
Holding money or property overseas does not necessarily mean that UK tax is due. The person’s tax residence, the source of the income, the nature of the asset and the relevant tax year all matter.
However, HMRC may receive financial account information from overseas jurisdictions through international exchange arrangements, including the Common Reporting Standard.
Reported data may include information about certain overseas accounts, account holders, balances and financial income. HMRC can compare that information with UK tax returns.
This is why an overseas account can lead to questions even when the taxpayer did not mention it directly to HMRC.
The data may still need careful checking. For example, an account could be jointly owned, held for another person or funded entirely from previously taxed capital.
Furthermore, the reported balance does not necessarily equal taxable income.
Our article on HMRC’s access to overseas banking information explains how international reporting can affect UK taxpayers.
Companies House and Land Registry Information
HMRC may use information available from public registers.
Companies House records can show:
- company appointments;
- filed accounts;
- persons with significant control;
- registered charges; and
- links between individuals and companies.
Land Registry records may provide information about property ownership and transactions in England and Wales. Separate systems apply elsewhere in the UK.
HMRC may compare these records with tax returns. For example, the sale of a property could prompt questions about Capital Gains Tax, while a person’s involvement in several companies may lead HMRC to examine income received from those businesses.
Again, public records do not always tell the complete story. Legal ownership, beneficial ownership and the tax treatment of a transaction may differ. Supporting documents can therefore become important.
Websites, Online Marketplaces and Social Media
HMRC’s published policy confirms that it may observe, record and retain publicly available internet material for compliance work.
This can include:
- business websites;
- online advertisements;
- marketplace listings;
- Companies House and Land Registry records;
- blogs;
- news reports; and
- public social media posts.
For example, a business website may advertise services or opening hours that appear inconsistent with declared turnover. Online listings may show regular sales activity, while public posts may suggest the use of an asset that does not appear in the business records.
Social media does not automatically prove anything. People exaggerate, reuse old photographs and post content that lacks context. Nevertheless, HMRC may use publicly available information to ask further questions.
Cash Deposits and Lifestyle Evidence
Cash businesses often attract particular attention because the accounting trail may be less direct.
HMRC may compare declared sales with:
- cash deposits;
- card receipts;
- stock purchases;
- supplier records;
- staffing levels;
- business opening hours; and
- typical profit margins.
Where records are incomplete, HMRC may try to reconstruct turnover using available evidence. However, any estimate should have a reasonable basis and reflect the particular business rather than rely on an unsupported assumption.
Personal spending may also become relevant. If somebody reports a very low income but appears to fund substantial mortgage payments, investments or other expenditure, HMRC may ask where the money came from.
There may be a legitimate explanation, such as savings, borrowing, gifts or an inheritance. The taxpayer will usually need records to support it.
Our guide I Was Paid in Cash — Is HMRC Really Able to Trace It? considers the evidence that can exist even where customers paid in cash.
Emails, Messages and Electronic Records
A document does not need to exist on paper.
Electronic accounting records, spreadsheets, emails, digital invoices and data held on business systems may all contain relevant information. HMRC’s guidance recognises that documents can exist electronically and that printed copies or electronic extracts may sometimes provide the necessary evidence.
In more serious cases, digital records may help establish when a document was created, whether figures changed or how a transaction developed.
Taxpayers should never alter or manufacture records after an investigation begins. If a record contains an error, preserve the original and explain the correction clearly.
Creating a false invoice or changing an existing document can turn a manageable tax enquiry into a much more serious matter.
Statements Made During the Investigation
Written explanations, telephone conversations and meeting notes can also affect an investigation.
A simple inconsistency may damage credibility if HMRC believes that the taxpayer keeps changing their account. However, memory is not always reliable, especially when the transaction happened several years ago.
Therefore, avoid guessing.
If you do not know the answer, say that you need to check the records. Then provide a considered response once you have established the facts.
Our step-by-step guide to responding to an HMRC letter explains why a careful first response can shape the rest of the enquiry.
Does HMRC Have Unlimited Powers?
No. HMRC has extensive powers, but legal limits and safeguards apply.
Under Schedule 36 of the Finance Act 2008, HMRC may require information or documents that are reasonably required to check a person’s tax position. Different rules apply depending on whether HMRC asks the taxpayer or a third party, and some categories of information receive protection.
Certain information notices can also carry rights of appeal. The exact position depends on who issued the notice, what HMRC requested and whether the relevant conditions apply.
Therefore, do not ignore a formal information notice. Equally, do not assume that every request must be answered without checking its scope.
An adviser can help determine whether HMRC’s questions are relevant, whether documents exist and whether any legal restrictions apply.
Evidence Should Be Considered as a Whole
One unexplained bank deposit does not necessarily prove undeclared income. A social media photograph does not prove ownership of an expensive asset. Likewise, a difference between two records may result from timing or accounting treatment rather than dishonesty.
HMRC may use individual pieces of information to build a wider picture. Taxpayers should do the same when preparing their response.
The strongest explanation usually connects the transaction to several consistent records—for example, a bank statement, loan agreement, accounting entry and correspondence from the lender.
The aim is not to overwhelm HMRC with paperwork. It is to provide the right evidence for the point that needs explaining.
Practical Guide
When HMRC asks for evidence, use the following approach:
| 1. Read HMRC’s request carefully | Identify the exact tax, period and issue under review |
| 2. Separate informal requests from formal notices | Different deadlines, safeguards and appeal rights may apply |
| 3. Preserve original records | Never alter or recreate documents without explaining what you have done |
| 4. Gather records from every relevant source | Include accounting systems, banks, emails and third parties |
| 5. Reconcile the information | Check whether the records agree with the submitted tax return |
| 6. Investigate unexplained differences | Transfers, loans and gifts may need supporting evidence |
| 7. Prepare a clear explanation | Link each important statement to a document or calculation |
| 8. Respond within the deadline | Ask for additional time promptly if genuinely necessary |
| 9. Keep a complete copy | Retain everything sent to HMRC and note when it was provided |
| 10. Seek advice where the risk is significant | Especially where HMRC alleges deliberate behaviour or requests extensive records |
Frequently Asked Questions
Can HMRC ask for personal bank statements?
HMRC may ask for personal bank statements where they are reasonably required to check the tax position. This may happen when business and personal funds were mixed or where HMRC needs to understand unexplained credits. The scope and relevance of the request should still be considered.
Does a bank deposit count as taxable income?
Not automatically. A deposit may represent income, but it could also be a loan, gift, transfer, inheritance or repayment. The taxpayer may need evidence showing where the money came from.
Can HMRC use social media as evidence?
HMRC may use publicly available online material for compliance work. However, a post or photograph may lack context and does not necessarily prove HMRC’s conclusion. A taxpayer should explain misleading material and provide reliable supporting evidence.
Can HMRC obtain information from overseas banks?
HMRC receives certain overseas financial account information through international exchange arrangements. It may also seek information through other lawful channels. The existence or balance of an overseas account does not itself establish the UK tax liability.
What if my records are missing?
Tell HMRC or your adviser which records are missing and why. You may be able to obtain copies from banks, suppliers, customers or software providers. Where reconstruction is necessary, use a reasonable method and explain it clearly rather than inventing figures.
Can I refuse to provide information to HMRC?
You should not ignore HMRC’s request. However, the answer depends on whether the request is informal or contained in a formal information notice, whether the information is reasonably required and whether any restriction or appeal right applies. Obtain professional advice before refusing.
Where to Find Official HMRC Information
For current official guidance, see:
- Tax compliance checks, explaining what HMRC may check and what can happen during an enquiry.
- Schedule 36 information and inspection powers, describing HMRC’s powers and the requirement for information to be reasonably required.
- HMRC’s open-source research policy, covering HMRC’s use of publicly available websites and social media.
- Electronic documents and computer records, explaining how HMRC may examine records held electronically.
- Common Reporting Standard guidance, explaining the international exchange of financial account information.
- Compliance checks factsheets, covering information notices, inspections, penalties and taxpayer rights.
HMRC’s powers and the taxpayer’s rights depend on the circumstances. Therefore, check the latest guidance and seek professional advice where necessary.
💡 Key Takeaway
HMRC rarely relies on one piece of evidence during a tax investigation. Instead, it compares tax returns with bank activity, business records, third-party information, overseas data and publicly available material.
An apparent difference does not always mean that tax has been underpaid. However, it does need a clear and credible explanation.
Preserve the original records, avoid guessing and support important statements with evidence. A careful, consistent response can prevent HMRC from drawing conclusions based on incomplete information.
Need Help?
If HMRC has opened a tax investigation or requested bank statements, business records or overseas financial information, Accounts Tax Group can help you understand the scope of the enquiry.
We can review HMRC’s questions, reconcile the available evidence and prepare a clear response on your behalf. Where records are missing or transactions require explanation, we can also help identify a reasonable way to reconstruct the position.
Contact Accounts Tax Group for confidential advice before responding to a significant HMRC information request.
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