What is the CIS monthly return deadline?

Your CIS monthly return must reach HMRC by the 19th after each tax month ends. Tax months run from the 6th to the 5th, so the month to 5 November 2026 is due by 19 November 2026.

If you pay self-employed trades for construction work, you are a contractor under the Construction Industry Scheme (CIS) and the monthly return is how you tell HMRC who you paid and what you deducted. GOV.UK says you file it through the HMRC CIS online service or commercial CIS software, and on each return you declare that the subcontractors listed are not employees.

The three monthly dates

You pay CIS deductions in the same way as PAYE and National Insurance. CIS 340 says that if the 22nd falls on a weekend or bank holiday, an electronic payment is due by the previous banking day.

Deadlines for the rest of 2026-27

If your average monthly payments to HMRC are below £1,500, including any PAYE, CIS 340 says you can pay quarterly. The returns are still monthly.

Nil returns since 6 April 2026

The rules changed this tax year. Nil returns were dropped in 2015 and are back from 6 April 2026, under the Income Tax (Construction Industry Scheme) (Amendment) Regulations 2026. A contractor whose business includes construction, and who has paid subcontractors before, must file a return showing no payments for any tax month in which nobody was paid, by the same 19th deadline.

There is one way out. The return is not needed if you told HMRC that you would make no payments in that month at least 14 days before it started. GOV.UK calls this an inactivity request. It lasts up to 6 months, you can renew it, and you can make one when you file a nil return through the CIS online service. Filing a return with payments on it ends the inactive period.

Deemed contractors, which are non-construction businesses spending more than £3 million on construction, are not legally required to file nil returns. But CIS 340 says HMRC still issues a penalty if they tell it nothing.

Penalties for late returns

After that, GOV.UK says an extra penalty of up to £3,000 or 100% of the deductions on the return, whichever is higher, may be charged. Each stage is added to the last. A return showing £1,200 of deductions that is 6 months late has picked up £100, £200 and £300, which is £600 in all, because 5% of £1,200 is only £60. On a return showing £8,000 of deductions, the 6-month penalty is £400.

Separately, GOV.UK says giving the wrong employment status for a subcontractor on a return could cost up to £3,000.

What this means for you

For a sole trader who takes on labour now and then, the risk is the quiet month. Before April 2026 there was no legal duty to file a nil return, although HMRC says some contractors who told it nothing ended up with penalties. Now a month with no payments still needs a nil return or an inactivity request in place at least 14 days before the month began. If your work comes in bursts, it is simpler to file the nil return each month than to remember the 14-day notice.

Steps to stay on time

1. Put the 19th and the 22nd in your diary every month, including months when you expect to pay nobody.
2. Verify each new subcontractor before you pay them, so you know the rate.
3. Record each payment, the materials and the deduction as you pay, not at the month end.
4. After the 5th, give each subcontractor their statement and file your return by the 19th, or a nil return if you paid no one.
5. Pay HMRC by the 22nd, or the banking day before if it falls at a weekend or on a bank holiday.
6. If no work is coming for a while, make an inactivity request well before the next tax month starts.

For the rest of the routine, read do I need to register as a CIS contractor and how to verify a CIS subcontractor. Use the free MTD check for your Making Tax Digital date, and the trades section has more on CIS.