Glazier
Tax & MTD Guide

For a self-employed glazier the tax picture is shaped by two things: a vehicle full of expensive kit, and the Construction Industry Scheme quietly skimming 20% off your labour on every contractor invoice. Get both right and you usually finish the year owed money by HMRC rather than owing it. Get them wrong and you either overpay through unclaimed CIS deductions or under-record the materials and tools that should be cutting your bill.

Whether you are replacing a smashed shopfront on a high street, fitting double-glazed units in a new-build, installing curtain walling on a commercial job, or doing emergency board-ups, the money tends to arrive net of CIS, with materials flowing through your books and a constant trickle of spend on blades, sealant and fuel. This guide is built around how a glazier actually earns and spends, so the annual return becomes a reconciliation rather than a scramble.

How Tax Works for a Self-Employed Glazier

As a sole trader you pay Income Tax on your profit, which is your total glazing income minus allowable expenses, not on the gross amount a contractor pays you. For 2026/27 the personal allowance covers the first £12,570, then you pay 20% to £50,270, 40% to £125,140 and 45% above, with the personal allowance tapering away between £100,000 and £125,140 to create an effective 60% band. Class 4 National Insurance is 6% on profit between £12,570 and £50,270 and 2% above, with Class 2 NIC settled through Self Assessment.

Scottish glaziers pay Scottish Income Tax through six bands (19%, 20%, 21%, 42%, 45% and a 48% top rate) and carry an S-prefixed tax code, while National Insurance stays UK-wide. Welsh glaziers have a C-coded tax code at rates currently matching the rest of the UK. If you also do PAYE work for a fabricator or installer and your code looks wrong, run it through the tax code checker so you are not taxed twice on the same allowance.

CIS: The Big One for Glaziers

If you install glazing as part of construction or building work for a contractor, you almost certainly fall inside the Construction Industry Scheme. Fitting windows, glazed units, shopfronts, curtain walling, partitions and structural glass for a contractor counts as construction operations. The contractor must deduct money from the labour element of your invoice and pay it to HMRC on account of your tax.

Two practical points decide how much CIS costs you up front. First, register as a CIS subcontractor so the rate is 20%, not 30%. Second, split labour and materials clearly on every invoice, because the deduction only applies to labour. If you bill £2,000 labour plus £1,500 for the glazing units, the deduction is 20% of £2,000, not the whole £3,500. Our full CIS subcontractor guide walks through registration, gross payment status and the statements you must keep.

Why You Are Usually Owed a Refund

The 20% deduction is a blunt instrument. It takes no account of your personal allowance, your van, your tools, your insurance or your materials. Once you deduct genuine business costs and apply the £12,570 personal allowance, your real tax bill on profit is frequently lower than the CIS already taken. At Self Assessment the deductions are credited against your Income Tax and Class 4 NIC, and the excess comes back to you. The CIS tax calculator shows the likely refund once your deductions and expenses are entered.

The one rule that protects this refund: keep every CIS payment and deduction statement from each contractor. Without them you cannot evidence what was withheld, and you risk losing the credit you are owed.

Allowable Expenses for Glaziers

An expense is allowable when incurred wholly and exclusively for the business. Glazing is equipment and vehicle heavy, so this list matters more than for most trades.

Tools, the Van and Capital Allowances

Big purchases such as a van, a scaffold tower or a full set of suction lifters are usually claimed through the Annual Investment Allowance, which lets you deduct the full cost in the year you buy, rather than spreading it. That can wipe out a large chunk of profit in a year you re-equip. For the van you choose one method and stick with it: either simplified mileage at 45p (then 25p over 10,000 miles), or the actual share of fuel, insurance, servicing, road tax and capital allowances on the vehicle. A glazier doing high mileage between sites should run both methods once and keep the larger.

What You Cannot Claim

The private share of a dual-use phone, van or fuel must be excluded. Everyday clothing is never allowable even if it gets wrecked on site, though branded workwear and genuine PPE are fine. Fines, parking penalties and the cost of your own driving licence are out. And ordinary commuting from home to a site you attend regularly is not deductible, even though travel between jobs during the day is.

Worked Example: A Glazier on £46,000 Turnover

Take a CIS-registered glazier doing mostly commercial shopfront and replacement work for contractors, with £46,000 of labour and materials billed for the year and £6,400 of CIS already deducted from labour.

Turnover: £46,000 (labour £32,000, materials £14,000)

Allowable expenses:

• Van running costs and capital allowance: £4,800
• Tools, suction lifters and access equipment (AIA): £2,200
• Materials bought for jobs: £9,000
• Public liability and tool insurance: £700
• PPE, workwear and waste disposal: £600
• Phone, home-office admin and accountancy: £900
• Total expenses: £18,200

Taxable profit: £46,000 minus £18,200 = £27,800

Income Tax: £27,800 minus £12,570 = £15,230 at 20% = £3,046

Class 4 NIC: £15,230 at 6% = £914

Tax and NIC due: £3,960. But £6,400 of CIS has already been deducted, so the glazier is owed a refund of roughly £2,440. Run your own labour, materials and CIS figures through the sole trader tax calculator to sanity-check the result before you file.

Record-Keeping on the Tools

Glazing record-keeping fails in the same place every year: receipts for sealant, blades, fixings and fuel that never made it out of the van. Build a habit of photographing each receipt the moment you pay, logging the mileage between jobs, and filing every CIS deduction statement as it arrives. Keep materials and labour separated on your own invoices so CIS is only ever applied to labour. Do this continuously and the annual return is a reconciliation, not an archaeology dig through a shoebox.

VAT and the Domestic Reverse Charge

You must register for VAT once taxable turnover passes £90,000 in any rolling 12-month period. Busy glaziers fitting commercial shopfronts and curtain walling reach this more often than they expect, especially when materials run through their books. Once registered, most construction services you supply to VAT-registered contractors fall under the domestic reverse charge: you do not add VAT to those invoices, and the contractor accounts for it instead. You must state on the invoice that the reverse charge applies and that the customer accounts for the VAT. Get this wording wrong and you risk charging VAT you should not, or losing it on a job where you should have. Work direct for private householders is normally standard-rated as usual.

MTD for Income Tax: What Changes for Glaziers

Making Tax Digital for Income Tax replaces the once-a-year return with quarterly digital submissions and a year-end finalisation. The thresholds are based on gross income, not profit and not take-home after CIS:

• April 2026: Combined gross trading and property income over £50,000
• April 2027: Over £30,000
• April 2028: Over £20,000

A subtle trap for CIS subcontractors: the threshold uses gross turnover before the 20% deduction, so a glazier taking home well under £50,000 after CIS can still be over the line on turnover. Instead of pulling a year of statements together each January, you record each invoice, material purchase and CIS deduction digitally as it happens and send HMRC a quarterly summary. Our guide to MTD for sole traders shows what the quarterly rhythm looks like on the tools.

Common Mistakes Glaziers Make

Not registering for CIS. Staying unregistered means 30% is deducted instead of 20%, tying up more of your cash with HMRC until you file.

Applying CIS to the whole invoice. The deduction is on labour only. List materials separately so the contractor does not over-deduct.

Losing the deduction statements. No statement, no evidence, no refund. File every one.

Mixing van methods. You cannot claim simplified mileage and actual running costs on the same vehicle in the same year. Pick one.

Judging the MTD threshold on take-home. It is measured on gross turnover before CIS and before expenses, so check your full billed income.

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