Guide
Appealing a CIS penalty - what counts as a reasonable excuse
How to appeal Construction Industry Scheme late filing or late payment penalties. Includes examples of reasonable excuses HMRC accepts and rejects, the appeal process with deadlines, and what evidence you need to support your case.
If you receive a penalty for late CIS returns or late payment of CIS deductions, you can appeal if you have a reasonable excuse. This guide explains what HMRC considers a reasonable excuse, how to appeal, and what evidence you need.
Understanding what constitutes a valid reason for appeal can save you from paying penalties you do not deserve - but it also helps you recognise when an appeal is unlikely to succeed.
When you can appeal a CIS penalty
You can appeal a CIS penalty if:
- You had a reasonable excuse for the failure (late filing or late payment)
- You believe the penalty has been calculated incorrectly
- You believe you should not have received the penalty (for example, you filed on time but HMRC did not receive it)
A reasonable excuse is something unexpected or outside your control that stopped you from meeting your CIS obligations on time. HMRC considers each case individually, but there are clear patterns of what they accept and reject.
Understanding CIS penalties
Before appealing, understand what penalty you have received and how it was calculated. CIS penalties escalate the longer you delay, so a quick appeal is important.
What HMRC accepts as a reasonable excuse
HMRC publishes guidance on what typically constitutes a reasonable excuse. The key principle is that the excuse must be genuine, unexpected, and directly cause the failure.
Real examples: accepted and rejected appeals
These examples illustrate how HMRC applies the reasonable excuse criteria in practice:
Appeals HMRC accepted
- Heart attack the week before deadline: Contractor suffered a heart attack 5 days before the return was due and was hospitalised for 10 days. Medical evidence provided. Appeal upheld - serious illness was unexpected and directly prevented compliance.
- Office fire destroyed records: Fire at business premises destroyed computer equipment and paper records 3 days before deadline. Fire service report and insurance claim provided. Appeal upheld - disaster was unexpected and records could not be recreated in time.
- HMRC online service was unavailable: Contractor attempted to file on 19th but received error messages. Screenshots showing attempts between 6pm and 11pm provided. Service status confirmed outage. Appeal upheld - HMRC system failure prevented timely filing.
- Death of spouse one week before deadline: Contractor's spouse died unexpectedly 8 days before return due. Bereavement affected ability to handle business matters. Death certificate and statement provided. Appeal upheld - recent bereavement is a recognised reasonable excuse.
Appeals HMRC rejected
- Accountant did not file on time: Contractor said accountant promised to file but forgot. HMRC rejected - responsibility remains with the contractor, and relying on someone else is not a reasonable excuse.
- Too busy with other work: Contractor said a large project meant they did not have time to file. HMRC rejected - pressure of work is not unexpected and deadlines are known in advance.
- Did not know about the deadline: New contractor claimed ignorance of filing requirements. HMRC rejected - ignorance of obligations is not a reasonable excuse. Information is publicly available.
- Computer crashed, lost data: Contractor's computer failed but they had no backups. HMRC rejected - routine IT problems are foreseeable. Businesses should have backup systems.
- Cash flow problems: Contractor could not pay accountant to file returns. HMRC rejected - financial difficulties do not excuse late filing (though may be considered for payment penalties in limited circumstances).
- Staff member left without notice: Person responsible for CIS returns resigned unexpectedly. HMRC rejected - businesses should have contingency plans. Staff turnover is foreseeable.
The appeal process
Appeals must follow a specific process with strict deadlines. Missing deadlines can make your appeal invalid.
Step-by-step: how to appeal
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Step 1: Gather your evidence
Collect all documents that support your reasonable excuse: medical certificates, death certificates, fire reports, screenshots of HMRC system errors, letters from utility providers about outages, or any other evidence that proves your excuse is genuine and caused the failure.
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Step 2: Check the deadline
You have 30 days from the date on the penalty notice to appeal. If you miss this deadline, you must explain why your appeal is late - and that explanation must also be a reasonable excuse.
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Step 3: Choose your appeal method
Appeal online through your Government Gateway account for the fastest response, or write to the address on your penalty notice. Online appeals receive immediate confirmation.
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Step 4: Write your appeal clearly
State your UTR, the penalty reference, what happened (briefly), why it was outside your control, what you did as soon as you could, and attach your evidence. Be factual and avoid emotional language.
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Step 5: Submit and wait
HMRC typically responds within 45 days. You do not need to pay the penalty while a valid appeal is being considered. Keep copies of everything you submit.
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Step 6: If rejected, consider further options
You can request an internal review by a different HMRC officer, or appeal to the First-tier Tax Tribunal within 30 days of HMRC's final decision.
Writing an effective appeal
Your appeal letter should be clear, factual, and supported by evidence. Here is a structure that works:
What to include
- Your details: Full name, business name, UTR, and CIS contractor reference
- Penalty reference: The reference number from your penalty notice
- What happened: A brief, factual description of the event that prevented compliance
- Why it was beyond your control: Explain why you could not have foreseen or prevented it
- When you complied: State when you filed the return or paid the deductions after the excuse ended
- Evidence attached: List the documents you are including
Example appeal letter opening
"I am writing to appeal the late filing penalty of [amount] dated [date], reference [penalty reference], relating to the CIS return for tax month [period].
On [date], I was admitted to hospital following a heart attack. I was unable to work or access my business records until [date]. As soon as I was discharged and able to work, I filed the return on [date]. I attach a letter from my GP confirming the dates of my illness and hospital admission."
What happens after you appeal
If HMRC accepts your appeal
The penalty is cancelled. If you have already paid it, HMRC will refund the amount to your CIS account or bank account.
If HMRC rejects your appeal
You have two options:
- Request an internal review: Ask for a different HMRC officer to look at your case. This is free and can sometimes succeed where the first appeal failed.
- Appeal to the Tax Tribunal: You have 30 days from HMRC's final decision to appeal to the First-tier Tax Tribunal. Tribunal appeals are independent of HMRC.
Tribunal appeals
The First-tier Tax Tribunal is independent of HMRC. You can represent yourself or use a tax adviser. For small penalties, the tribunal uses a paper-based process - you do not need to attend a hearing.
Tribunal fees:
- Basic cases (penalties under £20,000): No fee
- Standard cases: £50
- Complex cases: £200
Multiple penalties and appeals
If you have received penalties for multiple late returns, you must appeal each penalty separately. However, if the same reasonable excuse applies to all penalties (for example, a period of illness), you can include them all in one letter.
State clearly which penalty references you are appealing and confirm that the same excuse applies to each one.
Preventing future penalties
After dealing with the immediate penalty, take steps to avoid future problems:
- Set calendar reminders: The 19th of each month is your filing deadline. Set reminders for the 15th and 18th.
- File early: Do not wait until the 19th. Filing by the 14th gives you a buffer for problems.
- Request inactivity: If you will not have subcontractor payments for a period, request inactivity with HMRC rather than filing nil returns.
- Use software: Payroll software can automate CIS returns and send reminders.
- Have a backup plan: Ensure someone else in your business can file returns if you are unavailable.
Special circumstances during the April 2026 changes
From April 2026, HMRC is re-imposing the requirement to file nil returns. If you have been registered as inactive and are not aware of this change, HMRC may show some flexibility during the transition period.
However, this is not guaranteed. Check your CIS status and ensure you understand whether you need to start filing monthly returns again.