What expenses can a self-employed plumber claim?

A self-employed plumber can claim pipe, fittings, boilers and parts for jobs, tools, test kit, Gas Safe fees, relevant training, van costs and protective gear. In 2026-27, a basic rate taxpayer outside Scotland saves £26 per £100 claimed.

Each cost must be for your plumbing or heating business. If something is part personal, only the business share counts. For rules shared by every trade, see what expenses a self-employed tradesperson can claim. Below is what is particular to plumbing and heating work, checked against GOV.UK and HMRC guidance on 16 October 2026.

Plumber expenses: what usually counts

Under traditional accounting, tools, analysers and a van go through capital allowances instead. Since the cash basis is the standard method for sole traders, most plumbers deduct the full price in the year they pay.

Gas Safe and scheme fees

Under regulation 3 of the Gas Safety (Installation and Use) Regulations 1998, a self-employed person must not do work on a gas fitting unless they belong to a class of persons approved by the Health and Safety Executive. The government's competent person scheme list names the Gas Safe Register for gas appliances. Plumbers who self-certify bathrooms, water supply or heating and hot water work may also pay a scheme such as APHC, which the same list names for that work. These fees are costs of trading, so they come off your profit. A fee paid in the 7 years before you started trading is not lost: HMRC's pre-trading expenditure rules can still give relief for it, as long as it would have been allowable once you were trading.

Training: HMRC's own plumbing examples

HMRC's training guidance uses two examples straight from the trade. A plumber who takes a beginners' bookkeeping course can likely claim it, because it helps them run the business better. A gas boiler fitter who trains to install heat pump systems can likely claim it too, because they are keeping up with new technology in their industry. What does not count is a course to move into an unrelated line of work. Our guide to claiming training courses has more examples.

Where CIS fits for plumbers

Whatever a contractor deducts is tax paid early on your behalf, so it does not go in your expenses. Materials are worth recording separately on CIS invoices too: see does CIS apply to materials.

What this means for you

Say a plumber in 2026-27 drives 7,500 business miles (7,500 x 55p = £4,125), buys a flue gas analyser and press-fit tool for £1,900, pays £800 for Gas Safe and insurance, and takes a £1,200 heat pump course. That is £8,025 of costs. If profit stays in the basic rate band, outside Scotland that saves £1,605 of Income Tax at 20% and £481.50 of Class 4 National Insurance at 6%, £2,086.50 in all. This is an example only.

Steps to claim your plumbing expenses

1. Keep merchant receipts and note which job each part or boiler was for.
2. Keep your Gas Safe, scheme, insurance and calibration invoices for the year in one place.
3. Log business miles from home to each job, or keep fuel and servicing bills for actual costs.
4. Keep course invoices with a note of how the course relates to your existing work.
5. Split out personal use of your phone and van, and write down how you worked it out.
6. Enter costs weekly rather than at the year end, so your records are ready when Making Tax Digital quarterly updates start.

Not sure when quarterly updates begin for you? The free MTD check tells you, and the trades section covers how Making Tax Digital works for plumbers and heating engineers.