Contractors must tell HMRC each month about payments made to subcontractors, using the HMRC CIS online service or commercial CIS software. On the return the contractor declares that the subcontractors listed are not employees.
Returns must reach HMRC by the 19th of every month following the last tax month. For example, the return for the tax month 6 May to 5 June must reach HMRC by 19 June.
If you make deductions, you must give each subcontractor a payment and deduction statement within 14 days of the end of each tax month (for the tax month 6 May to 5 June, by 19 June).
File a nil return, or tell HMRC you have temporarily stopped using subcontractors (an inactivity request).
| How late | Penalty |
|---|---|
| 1 day | £100 |
| 2 months | £200 |
| 6 months | £300 or 5% of the CIS deductions on the return, whichever is higher |
| 12 months | £300 or 5% of the CIS deductions on the return, whichever is higher |
Later than this, an extra penalty of up to £3,000 or 100% of the CIS deductions on the return may apply. Giving the wrong employment status for a subcontractor can mean a penalty of up to £3,000.
Source: GOV.UK — file your monthly returns.
Last checked: 19 October 2026. Estimates only, not tax advice.
The 19th of the month after the end of the tax month (tax months run from the 6th to the 5th).