Gas engineers working under CIS face a specific combination of professional registration costs (Gas Safe is a significant annual expense), materials supply that is often excluded from the deduction base, and the same 20% deduction on labour income as every other CIS trade. The professional compliance costs are entirely allowable and often underchimed.
Gas Safe registration is a mandatory professional cost for gas engineers and is fully allowable as a business expense. Annual renewal, card fees and any inspection costs all qualify. Many gas engineers do not claim these correctly, partly because they are paid personally rather than through a business account.
Where you supply parts (gas valves, boiler controls, thermostats, cylinders), the cost of those materials is excluded from the CIS deduction base. If your contractor is applying the 20% rate to the full invoice rather than the labour element only, you are overpaying on every job that involves materials supply.
The van is your workshop. Fuel, insurance, road tax, MOT, servicing and finance charges on a van used for work are all allowable. From April 2026, the AMAP rate for a car or van is 55p per mile. Gas analysers, leak detection equipment and hand tools are all eligible for capital allowances.
We include Gas Safe fees, tool costs, van expenses and all other allowable deductions in your Self Assessment return to maximise your refund. Most gas engineers receive more than they expect when the full expense picture is captured.
Gas engineers with net CIS income over £30,000 can qualify for GPS and receive gross payments from main contractors. We manage the application and the compliance record.
Annual Self Assessment, quarterly MTD updates if required from April 2026, and proactive advice as your earnings grow.
Book a free call. We will talk through your CIS position, your deduction history and whether there is anything worth changing. No hard sell, no obligation.
Other trades we work with