Tax Guide for Self-Employed Bathroom Fitters

Bathroom fitting is construction work that falls under the Construction Industry Scheme (CIS) when you work for a contractor. If you work as a self-employed bathroom fitter, your contractor deducts 20% from your payments and sends it to HMRC. At the end of the tax year, you file Self Assessment — and the expenses you claim often mean a significant refund.

Bathroom fitters are multi-skill tradespeople — plumbing, tiling, and carpentry in one job. That breadth means a wider tool collection and higher material costs than single-trade workers, plus subcontractor costs for gas and electrical work you can't legally do yourself.

What You Can Claim

Expense	Examples	Typical Annual Cost
Plumbing tools	Pipe cutters, pipe benders (Irwin Hilmor ~£80), basin wrenches, water pump pliers	£100–£400
Tiling tools	Manual tile cutter, wet tile cutter (Vitrex ~£250), diamond hole cutters, grout floats	£100–£400
Power tools	SDS drill, multi-tool, jigsaw, angle grinder, cordless drill/driver	£200–£500
PPE & workwear	Safety boots, knee pads, dust masks, safety glasses	£150–£300
Vehicle costs	Van fuel, insurance, MOT, servicing, road tax	£4,000–£6,000
Materials & consumables	Pipes, fittings, silicone, sealant, adhesive, grout, tanking kits (~£130–£180 each)	£500–£2,000
Subcontractor costs	Gas Safe engineer for boiler/gas work, Part P electrician for bathroom circuits	£300–£1,500
Insurance	Public liability, tool cover	£80–£250
Training & certifications	CSCS card renewal, NVQ assessment fees	£100–£500
Phone & apps	Mobile contract (business portion), job management apps	£150–£300
Accounting fees	Tax return preparation, bookkeeping	£150–£400

Tanking and Waterproofing

Wet rooms and walk-in showers need proper waterproofing. A tanking kit (primer, membrane, sealing tape) costs £130–£180 per bathroom. If you buy these for jobs where they're not supplied by the client, they're fully deductible.

Subcontractor Costs: Gas and Electrics

You can't connect gas appliances or do notifiable electrical work in a bathroom without separate certification. If you include a Gas Safe engineer or Part P electrician in your quote and pay them directly, their cost is a deductible business expense. Bathrooms are classified as "special locations" for electrics, so most wiring work requires a qualified electrician.

HMRC Flat Rate Alternative

HMRC allows a £60/year flat rate deduction for tools and specialist clothing. For bathroom fitters, knee pads and tile cutters alone exceed this — claim the real figures with receipts.

Expenses You Can't Claim

Commuting to a regular workplace — travel to the same location for over 24 months isn't deductible. Travel to different customer bathrooms is deductible.
Everyday clothing — jeans and trainers don't qualify. Only specialist PPE counts (safety boots, knee pads, dust masks)
Your original fitting qualification — your initial NVQ isn't deductible. Only renewals, upgrades, and CPD count
Fines and penalties — parking tickets, PCNs, late-filing penalties
Food and drink — unless you're working away from your normal area overnight

Example: How Much Tax Does a Bathroom Fitter Pay?

Claire works as a self-employed bathroom fitter through CIS. Here's her 2025/26 tax year:

Item	Amount
CIS income (gross)	£40,000
CIS deducted (20%)	£8,000
Allowable expenses	£7,500
Taxable profit	£32,500
Income Tax (after £12,570 personal allowance)	£3,986
Class 2 NI (£3.50/week × 52)	£182
Class 4 NI (6% on £12,570–£50,270)	£1,196
Total tax + NI due	£5,364
CIS already deducted	£8,000
Refund due	£2,636

Without claiming expenses, her refund would be just £686. Expenses save Claire £1,950. You can claim back your CIS deductions through your Self Assessment return.

Record Keeping Tips

Save tanking kit and material invoices — waterproofing costs £130–£180 per bathroom. Keep invoices with the job address for each install
Track subcontractor payments — Gas Safe engineer and electrician invoices are deductible. Record the job, date, and amount for each subcontractor you pay
Keep separate receipts for plumbing and tiling supplies — pipes, fittings, adhesive, and grout often come from different suppliers. Photograph thermal receipts from builders' merchants the same day
Save your CIS payment statements — you need these to reclaim the 20% deduction. Chase your contractor for missing ones before 31 January
Log every job and journey — note the customer address and mileage for each bathroom install. Most fitters work at a different property each week

Key Deadlines

Deadline	What
5 April	Tax year ends — finalise your income and expense records
31 January	File Self Assessment and pay any tax owed (or receive your refund)
31 July	Second payment on account (if applicable)

If this is your first year, register for Self Assessment by 5 October after the tax year ends.

VAT Threshold

With day rates of £170–£300, experienced bathroom fitters working steadily can approach the £90,000 VAT threshold (2025/26) — especially those who supply bathroom suites alongside labour. At £250/day for 48 weeks, that's £60,000 from labour alone. Add material supply and your turnover climbs. Monitor your rolling 12-month total, which is based on turnover, not profit.

This guide is for informational purposes only and does not constitute tax, legal, or financial advice. Tax rules change frequently. Always verify current requirements on GOV.UK or consult a qualified accountant for your specific situation.

Official Sources

Expenses if you're self-employed — GOV.UK
Construction Industry Scheme — GOV.UK
Simplified expenses for vehicles — GOV.UK
Self-employed National Insurance rates — GOV.UK
Check if you need to register for VAT — GOV.UK