CIS accounting

Specialist accountants for bathroom fitters.

Bathroom fitting on new-build developments and commercial fit-outs falls squarely within CIS. Self-employed bathroom fitters have 20% deducted from their labour payments, but the significant cost of materials they supply (sanitaryware, baths, showers, enclosures, tiles, tanking materials and fittings) is excluded from the deduction base entirely. When a contractor fails to apply the split and deducts from the full invoice, the overpayment on a fully supplied bathroom installation is among the highest in the fit-out trades.

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20%

Deducted on labour (sanitaryware and materials excluded)

~£2,000

Illustrative first-year CIS refund

55p

AMAP mileage rate per mile from 6 April 2026

The specific challenges

What makes bathroom fitters accounting different.

Sanitaryware and materials excluded from the deduction base

A fully supplied bathroom installation can involve baths, basins, WC suites, shower enclosures, trays, taps, radiators, tiles, tanking membrane, adhesive and grout. All of these are materials that you supply for the job, and all of them should be excluded from the CIS deduction base. If your main contractor applies the 20% rate to the full invoice, the overpayment is substantial on every supplied installation. We review your deduction statements and identify where this error has occurred.

Private domestic work sits outside CIS

Many bathroom fitters combine CIS site contracts (new-build, commercial fit-out, main-contractor jobs) with direct private refurbishment work for homeowners. Work for a private homeowner is outside CIS because householders are not contractors. No deduction should be taken on those jobs, but the income is still taxable. Keeping the two income streams in separate records prevents errors at Self Assessment and ensures expenses are allocated to the right income type.

Tanking and waterproofing: confirming CIS scope

Tanking, shower tray installation, floor-to-wall waterproofing and structural alterations to bathroom spaces (such as removing or repositioning walls) are CIS-specified operations. Purely decorative tiling in a domestic private setting is a less clear area. Bathroom fitters who move between structural work and decorative finishing need to understand which part of each job is in scope to invoice and record correctly.

Tile cutting, specialist tools and equipment costs

Wet-cut tile saws, grout removal tools, tanking application equipment and power drills are capital expenditure eligible for capital allowances. Consumables such as cutting discs and blades are revenue expenses. We ensure every qualifying item is captured and claimed in the correct way.

How we help

What we do for bathroom fitters.

CIS refund with correct materials exclusion

We review every deduction statement, check whether sanitaryware and materials have been correctly excluded from the deduction base, account for all allowable expenses, and submit your Self Assessment return. Bathroom fitters with high materials costs typically recover considerably more than a self-filed return produces.

Private and CIS income separation

We structure your records so CIS site income and private domestic income are clearly separated, each with its own expense allocation. This ensures your Self Assessment return accurately reflects both income streams and that your expense claims are correct.

Gross payment status application

If your net CIS income (labour element, excluding materials) exceeds £30,000 per year, you may qualify for GPS. We calculate the correct net figure to account for the materials exclusion and manage the GPS application through all three qualifying tests.

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Questions from bathroom fitters

I supply the full bathroom suite and fittings and then install everything. Should CIS apply to the whole invoice?

No. The cost of materials you supply, including baths, WC suites, basins, shower enclosures, taps, tiles and tanking materials, is excluded from the CIS deduction base. Only the labour element of the invoice is subject to the 20% deduction. If your contractor is deducting from the full invoice value, you are overpaying and the difference is recoverable through Self Assessment.

I fit bathrooms for homeowners as well as on new-build sites. What is the difference for tax?

Work for a private homeowner is outside CIS because private householders are not contractors for CIS purposes. No CIS deduction should be taken on those jobs. However, the income is still taxable and must be included on your Self Assessment return. Your CIS site income and private income need to be recorded separately so that expenses are matched to the right source and your tax return reflects both correctly.

The GPS turnover test: does the materials I supply reduce my qualifying turnover?

Yes. The GPS turnover test uses net CIS income, which excludes materials. If your sanitaryware and fittings costs are high relative to your total invoiced amount, your qualifying net turnover will be lower than your gross invoiced figure. We calculate the correct net figure as part of any GPS assessment, because understating or overstating materials costs produces the wrong GPS eligibility picture.

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Talk to a specialist bathroom fitters accountant

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.

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Specialist in CIS and construction accounting, not a generalist practice

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24-hour response guarantee

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Fixed fees, quoted before we start

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Other trades we work with

Plumbers Electricians Joiners and Carpenters Groundworkers Roofers

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