Mistakes made by HM Revenue & Customs (HMRC) can be stressful for individuals and businesses alike. Whether it’s a miscalculated tax bill, a wrongly issued penalty, or incorrect personal information, it’s important to know your rights and the steps you can take to resolve the issue quickly and fairly.

Common HMRC Errors

Errors by HMRC may include:

• Incorrect PAYE codes
• Duplicate or missing tax returns
• Misapplied payments
• Erroneous penalties or surcharges
• Incorrect self-assessment calculations

In any of these scenarios, prompt action is key.

Step 1: Check the Details Thoroughly

Before contacting HMRC, make sure you understand the issue. Review all relevant paperwork, including correspondence, tax returns, and payment records. Often, discrepancies arise from incorrect or incomplete information provided during the filing process.

Step 2: Contact HMRC Directly

If you identify a mistake, contact HMRC as soon as possible. This can be done via phone, post, or through your HMRC online account. When speaking to an adviser, always note:

• The date and time of the call
• The name of the person you spoke to
• A summary of the conversation

Be clear and concise about the issue and provide any supporting documentation.

Step 3: Dispute a Penalty or Fine

If HMRC has issued a fine or penalty in error, you have the right to appeal. Typically, you must do this within 30 days of the penalty notice. Your appeal should explain:

• Why you believe the fine is incorrect
• Any reasonable excuse you may have (e.g., illness, postal delays, technical issues)
• Supporting evidence, such as bank statements or confirmation emails

In most cases, HMRC will pause enforcement while they consider your appeal.

Step 4: Ask for a Review or Make a Formal Complaint

If your issue is not resolved to your satisfaction, you can request a Statutory Review by an independent officer within HMRC. Alternatively, you can escalate the matter by submitting a formal complaint through HMRC’s complaints process. If you remain dissatisfied, the issue can be taken to the Adjudicator’s Office or Parliamentary and Health Service Ombudsman.

Step 5: Seek Professional Support

Resolving HMRC errors can be time-consuming and complex, particularly for businesses. Working with a professional accountancy firm can take the pressure off and ensure your case is properly presented.

CMA Accountancy, which specialises in supporting small businesses and self-employed professionals, advises clients not to ignore letters or demands from HMRC, even if they appear to be wrong. “We always recommend keeping clear records and getting in touch with an adviser early — in many cases, errors can be corrected quickly when handled correctly,” says a CMA spokesperson. “But failing to respond can cause a small issue to escalate unnecessarily.”

Final Thoughts

While HMRC strives for accuracy, mistakes do happen — and when they do, it’s crucial to act swiftly and stay calm. Keep detailed records, challenge incorrect information, and don’t hesitate to involve a trusted accountancy firm like CMA Accountancy to guide you through the process.

For further help, visit the HMRC complaints and appeals section on GOV.UK or consult a chartered accountant.