If you have missed a CIS deadline, act immediately. The longer you delay, the higher your penalties will be.
There are two key CIS deadlines each month:
- file your CIS monthly return by the 19th
- pay CIS deductions by the 22nd if you pay electronically, or the 19th if you pay by post
Missing either deadline triggers automatic penalties. However, acting quickly can prevent penalties from escalating.
Immediate action: File or pay now
Do not wait. Whether you are one day late or several weeks late, file your return and make your payment today. The penalty structure escalates the longer you delay.
If you missed the filing deadline (19th)
- Log in to the CIS online service today.
- Complete your CIS300 return. A partial return is better than no return.
- Check you have included every subcontractor payment.
- Submit it straight away, because the time you submit decides your penalty.
If you missed the payment deadline (22nd/19th)
- Work out the total CIS deductions you owe from your return or records.
- Pay by Faster Payments or CHAPS, which reach HMRC the same day.
- Use your 13-character Accounts Office reference plus the tax year and month as the payment reference.
- Keep proof of payment, as you may need it for an appeal.
Understanding the penalty structure
CIS late filing penalties escalate the longer you delay. Understanding this structure shows why acting immediately matters.
If you are only 1 day late
A fixed penalty of £100 applies immediately, but you can prevent further escalation:
File today to stop further penalties building up, and pay today to avoid interest and late payment penalties. If you have a reasonable excuse, appeal to cancel the penalty. Do not let embarrassment or putting it off turn a small penalty into a large one.
If you are more than 2 months late
By this point, you face fixed penalties of £300 (£100 plus £200). At 6 months, percentage-based penalties kick in:
File immediately, because every extra month adds to what you owe. Gather complete records for your return. If you are struggling, contact HMRC, which may be able to help you file correctly, or ask an accountant to help you catch up.
If you cannot pay the deductions you owe
Missing the payment deadline because you do not have the money is a serious situation, but there are options:
Time to Pay arrangement
HMRC offers payment plans for businesses struggling to pay their tax debts.
- CIS deductions are collected through the employers' PAYE system, and you may be able to set up an employers' PAYE payment plan online if you meet the conditions (broadly: all PAYE and CIS returns filed, the debt is within the online service's limit, and you can repay within 12 months - the online service checks your eligibility)
- For larger debts or complex situations, call the Payment Support Service.
- Plans typically run for up to 12 months, depending on your circumstances.
You must still file your return on time, even if you cannot pay. Late filing penalties are separate from late payment penalties. Filing on time while setting up a payment plan avoids the most damaging penalties.
What you need for a Time to Pay call
- Your business details and PAYE reference
- The amount you owe and which periods it covers
- Why you cannot pay (temporary cash flow, delayed payments from customers, etc.)
- What you can realistically afford to pay monthly
- When you expect to clear the debt
If you cannot pay your tax bill on time (opens in a new tab)
Filing a nil return late
If you made no payments to subcontractors during a tax month but failed to file a nil return, you still face penalties. HMRC does not know you had nothing to report - they assume you have failed to file.
What to do
- File the nil return through the CIS online service.
- If you do not expect to make subcontractor payments, request an inactivity period (up to 6 months) to avoid monthly filing requirements. The request must be in place no later than 14 days before the start of the tax month it covers
- If you genuinely had no obligation to file (for example, you were never actually a CIS contractor), you may be able to challenge the penalty
Since 6 April 2026 (SI 2026/289), if you are registered as a CIS contractor, you must file a return every month - including a nil return - unless you have requested inactivity or otherwise notified HMRC in advance.
Can you appeal the penalty?
You can appeal a CIS late filing penalty if you have a "reasonable excuse". However, HMRC has strict criteria for what counts as reasonable.
How to appeal
If you believe you have a reasonable excuse, you have 30 days from the date on your penalty notice to appeal.
Key deadlines reference
Every CIS tax month runs from the 6th of one month to the 5th of the following month. Here are the deadlines:
-
File your overdue CIS return immediately
Log in to the CIS online service at gov.uk and submit your CIS300 return now. The timestamp of your submission determines your penalty level.
-
Pay outstanding CIS deductions
Pay via Faster Payments or CHAPS for same-day receipt. Use your 13-character Accounts Office reference plus tax year and month.
-
Set up Time to Pay if you cannot pay in full
Call HMRC's Payment Support Service on 0300 200 3835 to discuss a payment plan before penalties escalate further.
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Appeal within 30 days if you have a reasonable excuse
Gather evidence (medical certificates, fire reports, HMRC system screenshots) and submit your appeal online or by post within 30 days of the penalty notice.
Legal basis
Primary legislation and key regulations