CIS accounting

Specialist accountants for glaziers.

Self-employed glaziers working on construction projects operate in one of the more technically specific CIS trades. Glass units, double-glazing sealed units, structural glazing components, aluminium frames, sealants and gaskets you supply are excluded from the CIS deduction base, yet glazing materials can represent a large proportion of a single contract value. The labour-only deduction rule, if applied correctly, significantly reduces the overpayment that most glazing subcontractors carry into each Self Assessment year.

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20%

Deducted on labour payments only

Deducted on glass units, frames and sealants

~£2,000

Average first-year CIS refund (illustrative)

The specific challenges

What makes glaziers accounting different.

High-value glass units excluded from the deduction base

Double-glazed sealed units, structural glass, curtain walling components and specialist glazing systems can carry significant unit costs. These materials are excluded from the CIS deduction base. If your main contractor applies the 20% deduction to the full contract value rather than the labour portion only, the overpayment on a single contract can run to hundreds of pounds. Over a year's work, it accumulates quickly. We check your deduction statements and identify every job where the split was not applied correctly.

Glazing installation versus repair: CIS scope

CIS applies to construction operations. Glazing installation as part of a new build or fit-out project is clearly within CIS. Straightforward glass repair and replacement carried out on a domestic property for a private homeowner is typically outside CIS. However, glass repair on a commercial building, or replacement forming part of a larger refurbishment contract, may still be within scope. The distinction matters because it determines whether a deduction should be made at all. If you carry out a mix of installation and repair across different contract types, we ensure each is classified correctly.

Specialist tools and glazing equipment

Suction lifters, glass cutters, frame sealant guns, drilling equipment and safety equipment for working with large glass panes all qualify as plant and machinery for capital allowance purposes. The Annual Investment Allowance provides a 100% first-year deduction on qualifying expenditure. Safety gloves, goggles and PPE required for glazing work are also allowable expenses.

Verification and the 30% rate

Glaziers who are not registered for CIS, or whose registration cannot be verified by a contractor, will have 30% deducted from labour income rather than 20%. If you have recently changed your trading name, address or UTR without notifying HMRC, verification may fail and the higher rate may be applied unnecessarily. We identify and resolve verification issues quickly.

How we help

What we do for glaziers.

CIS refund with correct materials exclusion

We review your deduction statements job by job, verify that glass, frames, sealants and gaskets are excluded from the deduction base, account for all allowable expenses, and submit your Self Assessment return. For glaziers with high glass costs on site, correctly applying the materials exclusion often produces a substantially larger refund than self-filed returns.

CIS scope review across contract types

If you carry out a mix of new installation work and repair or maintenance glazing, we review each income stream and ensure that CIS deductions are applied where they should be and not applied where they should not. Incorrectly treated income streams create errors in either direction on the Self Assessment return.

Gross payment status application

If your net annual CIS turnover (labour income, excluding glass, frames, sealants and VAT) exceeds £30,000, you may qualify for GPS and receive payments in full with no deduction. We handle the three qualifying tests, the application and the ongoing compliance.

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Questions from glaziers

I supply the glass units and frames on every job. Should CIS be deducted from the full contract price?

No. The cost of materials you supply, including double-glazed units, frames, sealants and gaskets, is excluded from the CIS deduction base. Only the labour element of the contract should attract the 20% deduction. If your contractor applies the deduction to the full contract value, you are overpaying on every job and that amount is recoverable through Self Assessment.

I replace broken windows in domestic properties for private clients. Do I need to register for CIS?

Probably not for that work specifically. CIS applies to payments made by contractors to subcontractors for construction operations. Where you invoice the homeowner directly for a straightforward glass repair or replacement on their domestic property, that transaction is generally outside CIS. CIS becomes relevant when you work as a subcontractor under a main contractor on a construction, refurbishment or commercial glazing project. If you carry out both types of work, the CIS-scope work and the non-CIS work need to be treated separately in your return.

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Talk to a specialist glaziers 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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