CIS Monthly Return Deadlines and Penalties (2025)
A clear 2025 calendar for CIS monthly returns, with deadline dates, penalties, and a simple workflow to stay compliant.
Not tax advice
Toolfy shares operational guidance, but you must confirm CIS and HMRC requirements with a qualified accountant who understands your business.
The Reality: CIS returns are simple but unforgiving. Missed filings trigger automatic penalties, and the risk multiplies the longer you wait. A clean monthly routine is cheaper than a backlog.
If you need the CIS basics first, read Complete CIS Tax Guide for Subcontractors 2026. If you need an invoice format that makes deductions easy, use: CIS invoice template (UK) for subcontractors. If you need to reconcile what you were deducted and keep proofs for year-end, use: CIS deduction statement explained + template.
The core deadline rule (remember this)
CIS returns are due by the 19th of each month for the previous tax month, which runs from the 6th to the 5th.
Example:
- Payments made between 6 June and 5 July
- Return due by 19 July
If the 19th falls on a weekend or holiday, file early to avoid penalties.
A simple monthly filing calendar
Use this structure every month:
- Tax month closes: 5th
- Reconcile payments: 6th to 10th
- Verify deductions: 11th to 15th
- File return: by 19th
What to prepare each month
Checklist:
- Subcontractor verification status
- Gross payment or deduction rates
- Payment totals per subcontractor
- Nil return confirmation if no payments
If you manage subcontractors regularly, see How to Hire and Manage Subcontractors in the UK.
Nil return template (copy and paste)
If you paid no subcontractors in the tax month, submit a nil return. Use a simple internal note:
Tax month: [date range]
Payments to subcontractors: None
Action: Nil return submitted on [date]
Store this note with your compliance records.
Penalties to avoid
HMRC penalties are automatic and escalate over time. The worst case is a chain of missed returns that triggers compliance review. The fix is simple: do not miss month one.
Evidence to store
Keep these together:
- CIS statements
- Subcontractor verification references
- Payment confirmations
- Return submission receipts
For year-end alignment, use End of Tax Year Checklist (31 March 2026).
How to make this routine painless
- Set a recurring reminder for the 6th and 15th
- Assign one owner for reconciliation
- Use a single template for every month
If you need a broader finance routine, review Small Business Accounting for Service Companies 2026.
Where Toolfy fits
Toolfy stores job and payment history in one place so you can export clean CIS reports for your accountant. Start a free trial if you want fewer manual reconciliations.
FAQ
Do I have to file if I only paid one subcontractor? Yes. Any CIS payment in the tax month requires a return.
Can I submit early? Yes. You can file once the payment month ends and you have the totals confirmed.
What if I paid no subcontractors? File a nil return to avoid penalties.
⚠️ Important Disclaimer
This guide is for general informational and educational purposes only. It does not constitute professional advice of any kind (legal, financial, tax, insurance, or otherwise).
Before making business decisions: Consult with qualified professionals (solicitors, accountants, insurance brokers, etc.) who can assess your specific circumstances. Laws, regulations, and industry standards change frequently and vary by location and situation.
Toolfy and the article authors accept no liability for decisions made or actions taken based on information provided in this guide. You are solely responsible for ensuring compliance with all applicable laws and regulations.
Frequently Asked Questions
When are CIS monthly returns due?
What happens if I miss a CIS return?
Do I have to file a return if there were no payments?
Need this workflow in Toolfy?
Spin up the exact checklist, scripts, and automations from this article inside your workspace.
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