Pre-notification of inactivity is the mechanism that allows a contractor registered under the Construction Industry Scheme to tell HMRC in advance that they expect to make no payments to subcontractors for a defined future period, suspending the monthly CIS300 filing obligation for that window.
From 6 April 2026, when the nil-return obligation was reinstated, the alternative of pre-notifying inactivity became more commercially important. Without it, a contractor who knows their project pipeline is empty for three or four months must still file a CIS300 nil return by the 19th of each following tax month, or face an automatic £100 penalty per missed return.
A contractor notifies HMRC of inactivity by contacting the HMRC CIS helpline (0300 200 3210, Monday to Friday 8am to 6pm) or through their contractor record online. The period can cover up to six months at a time. If subcontractor payments resume before the end of the declared inactive period, the contractor must notify HMRC and file returns for those active months. Failing to do so leaves a gap in the return record that HMRC may treat as non-compliance.
Pre-notification does not relieve a contractor of other CIS obligations. Verification of any new subcontractor, record-keeping, and payment and deduction statement requirements all continue. It is the monthly filing obligation only that is suspended for the inactive period.
- Maximum advance period: six months per notification.
- Method: HMRC CIS helpline or online contractor account.
- Effect: suspends CIS300 filing obligation for the notified period.
- Important: if payments resume early, inform HMRC and file for the active months.
The nil-return rule that makes this option relevant is explained in detail at CIS nil return explained. The full contractor monthly checklist, including when to use inactivity notification, is at CIS for contractors: your monthly responsibilities checklist.