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The CIS and tax calendar
Every date a trade business is judged on, in the order it arrives. Two of them are three days apart and catch people constantly: the return is due on the 19th and the money on the 22nd.
Every date a trade business is judged on, in the order it arrives. Two of them are three days apart and catch people constantly: the return is due on the 19th and the money on the 22nd.
A tax month runs from the 6th of one month to the 5th of the next. Everything below is measured from the end of that month, not from the calendar month.
| Date | What is due | Detail |
|---|---|---|
| 19th | Monthly CIS return | Within 14 days of the end of the tax month. From 6 April 2026 a nil return or a notification of inactivity is required from mainstream contractors where no subcontractors were paid. |
| 19th | Payment and deduction statements | To every subcontractor you deducted from, in the same 14 days. Where the deduction was at the higher rate the statement must carry the verification reference, complete with any letter on the end. |
| 22nd | Deductions paid to HMRC | If you pay electronically. The 19th if you still pay by post. The penalty runs from the return, not from the payment, so these are two separate exposures. |
CIS records must be kept for at least three years after the end of the tax year they relate to.
The penalties escalate on a fixed scale, and the appeal window is 30 days from the penalty notice.
| 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 | A further £300 or 5%, whichever is higher |
| More than 12 months | In the most serious cases, up to £3,000 or 100% of the CIS deductions, whichever is higher |
Each update is cumulative from the start of the tax year — it covers the year to date rather than just the quarter. Qualifying income is gross turnover from self-employment and property, before expenses.
| Period | Deadline |
|---|---|
| 6 April – 5 July | 7 August |
| 6 April – 5 October | 7 November |
| 6 April – 5 January | 7 February |
| 6 April – 5 April | 7 May |
There are no penalties for missing a quarterly update deadline in 2026/27. Late submission then moves to a points-based system, with a penalty at four points. Late payment percentages have already increased, and in your first year in the regime you get 30 days from the due date before penalties start rather than 15.
These are the ones that do not move, and the ones where a payment on account catches people in their second year of trading.
| Date | What is due | Who |
|---|---|---|
| 5 April | End of the tax year | Sole traders and partnerships |
| 31 May | P60 to every employee on the payroll at 5 April | Employers |
| 6 July | P11D and P11D(b) for benefits — including the van benefit charge | Employers |
| 31 July | Second payment on account for the tax year just ended | Sole traders and partners |
| 31 January | Self Assessment return, the balancing payment, and the first payment on account for the current year | Sole traders and partners |
| 9 months and 1 day after the year end | Corporation tax payment | Companies |
| 12 months after the year end | CT600 corporation tax return | Companies |
The 31 January bill is the one that catches a newly profitable trade business, because it is not one payment — it is the balance of last year plus the first instalment of this year. A business whose profits have just doubled can face something close to one and a half years of tax on the same day. That is a cash-flow problem to plan for rather than a mistake, and it is a large part of why the CIS deductions you have already suffered need to be reconciled properly: they are sitting against exactly that liability.
Returns filed by the 19th, statements out in the same window, and the deductions paid by the 22nd — without you having to hold three dates in your head every month.
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