Does CIS apply to repairs and maintenance work?

Mostly yes. As of October 2026, repairs to buildings, alterations and decorating are covered by CIS on new and existing property. Repairing, servicing or extending heating, wiring and plumbing systems on its own is not.

The Construction Industry Scheme (CIS) is not limited to new builds. Section 74 of the Finance Act 2004 covers the construction, alteration, repair, extension, demolition and dismantling of buildings and structures. HMRC's CIS manual and CIS 340 guide set out how repairs and maintenance fit, and this page follows them as checked on 17 October 2026.

Repairs to the building are covered

CIS 340 says a repair includes "making good" and replacing defective or damaged parts of a building or structure. Re-tiling part of a roof, replacing a rotten window frame, patching plaster and repairing brickwork all fall in. So do installing and repairing kitchens, bathrooms, glazing and doors, which CIS 340 lists by name.

Painting and decorating the inside or outside of any building is covered too, whether it is a new build or a repaint. HMRC's manual includes varnishing, French polishing of fixed woodwork, and sealants or anti-graffiti coatings sprayed onto a surface.

Repairs to systems are not

The law covers installing systems of heating, lighting, power, drainage, sanitation, water supply, ventilation, air conditioning and fire protection. HMRC reads that as installation only. Repairing, maintaining, altering or extending a system is outside CIS.

The manual's examples of repairs outside CIS are soldering a leaking pipe, replacing a defective tap, rewiring a single circuit, replacing a broken wash basin and fitting thermostatic radiator valves. Replacing a boiler is still a repair, even though it is a big part of the system. Adding a radiator or extra sockets is an extension, also outside. Replacing a whole system, such as a complete rewire, counts as installation and is covered.

Where a small job becomes a CIS job

Each "all of it" row is the mixed contract rule. HMRC's manual says that if any part of a contract relates to construction work, every payment under that contract is covered, even payments for work that would otherwise be excluded and even if invoiced separately. The manual also says that a contract to repair a system which includes any making good to the building brings every payment under it into CIS.

New build or old, house or office

What the building is does not matter. Who pays you does. CIS 340 says private householders having work done on their own home, including "decoration, repairs or an extension", are not contractors, so a homeowner pays you in full. The homeowner guide has more on this.

Other payers can be contractors for repairs. Builders, property developers and businesses whose work includes construction are mainstream contractors. A business outside construction becomes a deemed contractor once it spends more than £3 million on construction in 12 months. CIS 340 adds that a managing agent who takes on a maintenance contract and hires trades in its own name acts as a contractor.

What this means for you

A maintenance or reactive repairs trade can be in and out of CIS on the same day. Look at each contract, not your trade name. If a contractor deducts CIS from a pure system repair, ask them to check HMRC's manual. If a job includes making good, expect CIS.

Payments outside CIS are still business income for your tax return and count towards your Making Tax Digital income. You just have no deduction already paid towards the tax on them, so put money aside.

Steps to check a repair or maintenance job

1. Ask who is paying. A homeowner paying for their own home is not a CIS contractor.
2. Ask whether you are repairing the building or a system. Building repairs and decorating are covered. System repairs alone are not.
3. Check the contract for making good, roof work or other building repairs. Any one brings every payment under the contract in.
4. If CIS applies, give the contractor your Unique Taxpayer Reference, the name you registered under and your National Insurance number so they can verify you. Registered subcontractors have 20% deducted and unregistered ones 30%.
5. Keep the contract or job sheet with the invoice, so you can show why CIS did or did not apply.

The free MTD check shows when Making Tax Digital starts for you, and the trades section has more on CIS, including what work CIS covers.