CIS registration is the process of telling HMRC that a business is either a contractor that will be paying subcontractors, or a subcontractor that will be receiving CIS payments, or both at the same time.
Registration works differently depending on which role you are registering for:
- Contractors must register before making the first payment to a subcontractor. Registration is mandatory, not optional. A contractor who pays a subcontractor without being registered risks penalties for the unpaid deductions and interest.
- Subcontractors do not have to register, but without registration they are taxed at 30% on the labour portion of every payment rather than the 20% rate that applies to registered subcontractors. In practice, registration is essential for anyone doing regular CIS work.
To register, a subcontractor needs a valid Unique Taxpayer Reference (UTR) and, if they are a limited company, their company registration number. Sole traders also need their National Insurance number. Registration is done through the HMRC CIS online service or by calling the CIS helpline on 0300 200 3210 (Monday to Friday, 8am to 6pm).
After registration, the next step up for subcontractors is applying for Gross Payment Status, which removes CIS deductions altogether (0% rate). GPS requires passing a business test, a turnover test (at least £30,000 net CIS turnover for a sole trader) and a compliance test (all tax obligations met on time for the past 12 months).
Registration does not expire automatically, but HMRC can remove it (and GPS) if a subcontractor's compliance falls short. From April 2026 GPS can also be revoked immediately without advance notice under Finance Act 2026 where fraud is suspected in the supply chain.
See how to register for CIS and Gross Payment Status for the next steps after registration.