CIS nil returns
Since 6 April 2026, if your business does construction work, has paid subbies before and pays none in a tax month, you must file a nil return by the 19th. To skip it, tell HMRC at least 14 days before the tax month starts that you won't pay any subbies in it.
Who has to file a CIS nil return
You need one for a tax month when all three of these are true:
- your business does construction work (HMRC calls you a mainstream contractor)
- you have paid subbies under CIS before
- you paid no subbies at all in that tax month
The nil return is due on the same day as any other CIS300, within 14 days of the end of the tax month: the 19th. For the tax month 6 May to 5 June, that is 19 June. Every month's date is in CIS deadlines.
If you are a deemed contractor (a business outside construction that spends enough on construction to fall into CIS), the law does not make you file a nil return. HMRC still issues a penalty if you neither file one nor tell it you are inactive, and cancels it once you confirm you paid no subbies.
How to tell HMRC you won't pay any subbies
You don't need a nil return for a tax month if you told HMRC in advance that you would pay no subbies in it. The notice must reach HMRC at least 14 days before the tax month starts. For the tax month starting 6 June, that means by 23 May. Tell HMRC later than that and the regulations still need a nil return for that month.
HMRC's own guide, CIS 340, says it won't charge a penalty if you file a nil return or tell it you are inactive by the 19th. The regulations set the earlier date for the notice, so telling HMRC at least 14 days before the month starts is the safe way.
HMRC calls this making your CIS scheme inactive, and sets it for up to 6 months at a time. You tell it through HMRC's CIS online service or CIS software, or by ticking the inactivity box on a return you file.
If you start paying subbies again
Pay a subbie during an inactive period and you file a return for that month as normal. Filing it ends the inactive period. If you then expect no more payments, you can tick the box on that return to set a new inactive period of up to 6 months.
What happens if you don't file a nil return
A nil return is a CIS return like any other, so a late one gets the same penalties: £100 the day after the 19th, then £200 at 2 months and at least £300 at 6 months. Once you have filed a CIS return before, a month with no subbies paid can cost you £600 by then. See CIS late filing penalties for the full list and what counts as a reasonable excuse.
Nil returns before 6 April 2026
From April 2015 to April 2026 there was no legal duty to file a nil return. The rule came back on 6 April 2026, so it covers every tax month from the one starting that day.