What to do if you've missed a CIS deadline

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)

1. Log in to the CIS online service now - do not wait until tomorrow
2. Complete and submit your CIS300 return - even if incomplete, a partial return is better than no return
3. Include all subcontractor payments - double-check you have not missed any
4. Submit immediately - your submission timestamp determines your penalty

If you missed the payment deadline (22nd/19th)

1. Calculate the total CIS deductions owed - check your return or records
2. Pay via Faster Payments or CHAPS - these reach HMRC the same day
3. Use your correct payment reference - your 13-character Accounts Office reference plus the tax year and month
4. Keep proof of payment - you may need this 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 pounds applies immediately, but you can prevent further escalation:

• File today - stop the clock on additional penalties
• Pay today - avoid interest and late payment penalties
• Consider an appeal - if you have a reasonable excuse, you may be able to cancel the 100 pounds penalty (see below)

One hundred pounds is manageable. Do not let embarrassment or procrastination turn it into 300 pounds, 600 pounds, or more.

If you are more than 2 months late

By this point, you face fixed penalties of 300 pounds (100 pounds plus 200 pounds). At 6 months, percentage-based penalties kick in:

• File immediately - every additional month adds to your liability
• Gather your records - you will need complete information for your return
• Contact HMRC if struggling - they may be able to help you file correctly
• Consider professional help - an accountant can help you catch up and may spot issues you have missed

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. You can:

• Set up a plan online - 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)
• Call the Payment Support Service - for larger debts or complex situations
• Agree a schedule - typically up to 12 months, depending on your circumstances

Critical point: 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

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

1. File the nil return now - use the CIS online service
2. Request inactivity for future months - 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
3. Consider an appeal - 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): Nil return requirements apply strictly. 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.

Preventing future missed deadlines

Once you have dealt with the immediate situation, put systems in place to prevent this happening again:

Set up reminders

• Calendar alerts - set reminders for the 15th (prepare return), 19th (file), and 22nd (pay)
• Recurring tasks - make CIS compliance a monthly routine
• Backup contact - ensure someone else knows the deadlines if you are unavailable

Streamline your process

• Keep records current - record subcontractor payments as you make them, not at month end
• Use payroll software - many packages automate CIS calculations and filing
• Verify subcontractors promptly - do not leave verification until the return is due
• Set aside the deductions - transfer CIS amounts to a separate account so the money is available to pay HMRC

Consider using an accountant or payroll bureau

If CIS compliance is taking too much time or causing stress, professional help may be worth the cost. An accountant or payroll bureau can:

• Handle monthly CIS returns for you
• Ensure deadlines are met
• Verify subcontractors on your behalf
• Spot compliance issues before they become penalties

Important: Even if you use an agent, you remain legally responsible for CIS compliance. Agent failure is not a reasonable excuse for late filing.

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:

Next steps

1. File your late return now - do not wait another day
2. Pay any outstanding CIS deductions - use Faster Payments for same-day arrival
3. Set up a Time to Pay arrangement - if you cannot pay in full
4. Gather evidence for an appeal - if you have a reasonable excuse
5. Put prevention measures in place - calendar reminders, better record keeping, or professional help

The most important thing is to act today. Every day of delay increases your penalties and makes the situation harder to resolve.