Key facts
- Monthly CIS returns are due by the 19th of the month following the tax month.
- CIS deduction payments are due by the 19th (post) or 22nd (electronic) of the following month.
- Late filing penalties start at £100 and can reach £3,000+ for returns over 12 months late.
- The CIS tax year runs from 6 April to 5 April, divided into 12 tax months.
- Nil returns have the same deadline as regular returns — there is no exemption for months with no payments.
CIS Deadlines at a Glance
CIS contractors face multiple recurring deadlines throughout the year. Missing any of them can result in penalties and interest charges. Here is a consolidated view of all key CIS deadlines:[1]
| Obligation | Deadline | How to File/Pay |
|---|---|---|
| Monthly CIS return (CIS300) | 19th of following month | Online (HMRC or commercial software) |
| CIS deduction payment (post) | 19th of following month | Cheque to HMRC |
| CIS deduction payment (electronic) | 22nd of following month | Online banking, BACS, direct debit, CHAPS |
| Payment and deduction statement to subcontractor | Within 14 days of end of each tax month | Written statement (paper or electronic) |
| Nil return (no payments made) | 19th of following month | Online (same as regular return) |
Monthly Deadline Calendar (2026/27)
Below is the full calendar of CIS return and payment deadlines for the 2026/27 tax year:[1]
| Tax Month | Period | Return Due | Payment Due (Electronic) |
|---|---|---|---|
| 1 | 6 Apr – 5 May 2026 | 19 May 2026 | 22 May 2026 |
| 2 | 6 May – 5 Jun 2026 | 19 Jun 2026 | 22 Jun 2026 |
| 3 | 6 Jun – 5 Jul 2026 | 19 Jul 2026 | 22 Jul 2026 |
| 4 | 6 Jul – 5 Aug 2026 | 19 Aug 2026 | 22 Aug 2026 |
| 5 | 6 Aug – 5 Sep 2026 | 19 Sep 2026 | 22 Sep 2026 |
| 6 | 6 Sep – 5 Oct 2026 | 19 Oct 2026 | 22 Oct 2026 |
| 7 | 6 Oct – 5 Nov 2026 | 19 Nov 2026 | 22 Nov 2026 |
| 8 | 6 Nov – 5 Dec 2026 | 19 Dec 2026 | 22 Dec 2026 |
| 9 | 6 Dec – 5 Jan 2027 | 19 Jan 2027 | 22 Jan 2027 |
| 10 | 6 Jan – 5 Feb 2027 | 19 Feb 2027 | 22 Feb 2027 |
| 11 | 6 Feb – 5 Mar 2027 | 19 Mar 2027 | 22 Mar 2027 |
| 12 | 6 Mar – 5 Apr 2027 | 19 Apr 2027 | 22 Apr 2027 |
Tip: Set up calendar reminders for the 15th of each month to give yourself a few days’ buffer before the 19th filing deadline. Many contractors find it helpful to file the return and make the payment on the same day.
Late Filing Penalties
Penalties for late CIS returns are automatic and escalate the longer the return is overdue:[2]
| Lateness | Penalty | Notes |
|---|---|---|
| 1 day late | £100 | Immediate fixed penalty |
| 2 months late | £200 (additional) | Added to the £100 = £300 total |
| 6 months late | £300 or 5% of deductions (whichever is greater) | Tax-geared penalty kicks in |
| 12 months late | £300 or 5% of deductions (whichever is greater) | Additional tax-geared penalty |
These penalties apply per return. If you miss three monthly returns, you face three sets of penalties. The maximum penalty for a single return that is 12+ months late is £3,000 or more, depending on the deductions involved.
Payment Deadline Details
CIS deduction payments follow the same deadlines as PAYE:[3]
- 19th of the following month if paying by cheque (the cheque must reach HMRC by this date)
- 22nd of the following month if paying electronically (online banking, BACS, direct debit, CHAPS)
- If the deadline falls on a weekend or bank holiday, payment must reach HMRC by the last business day before the deadline
Other CIS-Related Deadlines
| Obligation | Deadline |
|---|---|
| Verify a new subcontractor | Before making the first payment |
| Register as a CIS contractor | Before making the first subcontractor payment |
| Subcontractor payment & deduction statement | Within 14 days of end of tax month (i.e. by 19th of following month) |
| Annual review of gross payment status | HMRC reviews around March/April each year |
| Self Assessment for subcontractors (reclaiming deductions) | 31 January following end of tax year |
Subcontractors: Remember that your Self Assessment tax return (deadline 31 January) is where you reclaim CIS deductions suffered. If you miss this deadline, you may face your own late filing penalties and delay in reclaiming your CIS overpayments.
Frequently Asked Questions
When is the CIS return deadline?
The CIS return for each tax month (6th to 5th) must be filed by the 19th of the following month. For example, the return for the tax month 6 July to 5 August must be filed by 19 August.
When must I pay CIS deductions to HMRC?
CIS deductions must be paid by the 19th of the following month if paying by cheque, or the 22nd if paying electronically. The payment deadline aligns with the PAYE payment deadline.
What happens if I file one day late?
A late filing penalty of £100 applies from the first day the return is late. Even being one day late triggers the penalty. Additional penalties accrue for continued lateness: £200 at 2 months, £300 (or 5% of the deductions, whichever is higher) at 6 and 12 months.
Do bank holidays affect CIS deadlines?
The filing deadline of the 19th does not change for bank holidays or weekends — the return must be received by HMRC by the 19th regardless. For payments, if the deadline falls on a non-business day, the payment must reach HMRC by the last business day before the deadline.
Further Reading
- Monthly CIS Returns (CIS300) — what to include on each return
- CIS Nil Returns — filing when there are no payments
- Paying CIS Deductions to HMRC — payment methods and references
- CIS Penalties for Late Filing & Payment — the full penalty regime
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Sources
- File your CIS monthly return — GOV.UK
- CIS late filing penalties — GOV.UK
- Pay CIS deductions to HMRC — GOV.UK