Window fitter
invoice template

Window fitters invoice homeowners, retailers and contractors for replacing windows and doors, often as subcontractors to a window company. Below is a ready-made window fitter invoice template, with worked example lines, the VAT and payment rules that apply, and the mistakes that most often delay payment.

What goes on a window fitter invoice

List each window or door with its location, size and style, removal and disposal of old frames, making good, and the certificate reference for building regulations compliance.

Line by line: Replace uPVC casement windows, 6 × £520.00 = £3,120.00; Composite front door, supply and fit, 1 × £1,350.00 = £1,350.00; Remove and dispose of old frames, 1 job × £180.00 = £180.00. The subtotal is £4,650.00. VAT at 20% adds £930.00, so the total is £5,580.00. The figures are illustrative, not a price guide, so use your own rates.

The legal minimum is the same for every trade. GOV.UK says an invoice needs a unique number, your business name and address, the customer's name and address, a description of the work, the supply date and invoice date, the amount charged, VAT if you charge it, and the total due. This template lays each of those out for window fitters; for the detail, read what a UK invoice must include.

Give each invoice the next number in a single sequence and never reuse one. A cancelled invoice keeps its number and is cancelled with a credit note. If you want a format that stays tidy for years, try the invoice number generator.

How window fitters price their work

Priced per window by size and style, with doors, bays and making good as separate items.

Keep the pricing visible. Each line should show the quantity, the unit and the rate, so the customer can match it to the quote. To set rates that cover your costs and your tax, try the day rate calculator; for materials and stock you resell, the profit margin calculator shows the margin you really make.

Agree this before you start

Agree measurements (done by you), styles and colours, glazing specification, lead times, making good inside and out, and the certification scheme you register the installation with.

When to send a window fitter invoice

Deposit at order, balance on completion and certification.

An invoice sent on the day tends to be paid on time; one sent weeks later tends to be paid weeks later. Email it as a PDF and keep a copy. The invoice due date calculator shows exactly when payment falls due under your terms.

VAT on window fitter invoices

Replacement windows and doors are standard-rated. Draught stripping is an energy-saving material, but new windows are not.

Once registered, window fitters charge 20% on most work to existing homes and commercial buildings. The reliefs are narrow: zero rate for building a new dwelling, 5% for converting a building into homes or renovating one empty for at least two years, and zero rate on qualifying energy-saving installations in homes until 31 March 2027. When a job mixes rates, put each on its own line so the VAT on the invoice can be checked.

Registration is compulsory once taxable turnover in the last 12 months passes £90,000, or when you expect to pass it within the next 30 days. Check your position with the VAT registration checker; until then, see invoicing without a VAT number.

CIS: when a contractor pays you

Working for a contractor brings you into CIS. The contractor verifies you with HMRC, then takes 20% (registered) or 30% (not registered) from the labour on each payment, or nothing if you have gross payment status. Materials are not subject to the deduction, which is why a CIS invoice splits labour from materials. The deductions are not lost: they are credited against your Income Tax and National Insurance, and your monthly statements from the contractor are the evidence.

Installation of glazing and doors is a construction operation within CIS for contractor work.

The CIS calculator shows what you receive after the deduction, and CIS invoice requirements sets out the invoice layout contractors expect.

The domestic reverse charge

When both sides are VAT registered and the job is reportable under CIS, the customer, not you, usually pays the VAT to HMRC under the domestic reverse charge. Your invoice shows the VAT that would have been due and a note that the reverse charge applies, but leaves it out of the total. End users, such as homeowners and businesses improving their own premises, pay VAT in the normal way. Check each case with the reverse charge checker and copy the invoice wording.

Working for homeowners

When the customer is a household rather than a business, consumer law sets the ground rules. A job agreed in someone's home, or by phone or online, normally carries a 14-day cancellation right under the Consumer Contracts Regulations. Starting earlier is fine when the customer asks, but record that request in writing, and bill only for work done if they later cancel.

Deposits, stages and cancellations

Deposits of 25% are common for made-to-measure frames.

Tie each payment to something the customer can see: a deposit when the booking is confirmed, then a stage payment at each agreed milestone, then the balance when the job is signed off. Commercial customers sometimes hold a retention against defects. If they do, invoice for the full stage and show the retention as a deduction with the date it falls due.

Payment terms for window fitters

Balance due on completion.

Between businesses, the default when nothing is agreed is 30 days from receipt of the invoice or the work, whichever comes later, and agreed terms should not normally exceed 60 days. Late business payers owe statutory interest at 8% above Bank Rate plus fixed compensation per invoice; the late payment interest calculator does the sums. Private individuals are not covered by that Act, so agree your terms with them in writing before the work starts.

Getting paid faster

Put everything the customer needs to pay on the invoice: your bank name, account name, sort code and account number, and the reference to use, normally the invoice number. Give a due date, not just "on receipt". Then follow a routine: a reminder the day after the due date, another a week later, and a firmer letter after two weeks. Most late payment is disorganisation, not refusal, and a routine fixes it. Invoice payment terms compares the common options, and the due date calculator turns them into a date.

If a customer disputes the invoice

When a customer queries an invoice, reply quickly and in writing, quote the quote or agreement, and ask them to pay the part they accept while you resolve the rest. A credit note can settle a partial dispute cleanly. Unpaid after reminders? Send a letter before action with a final date; in England and Wales, claims up to £10,000 can then go to the small claims track. Invoice disputes and small claims for an unpaid invoice have the detail.

Common window fitter invoicing mistakes

• No certificate reference. Replacement windows need building regulations compliance; reference the certificate from your scheme.
• Making good not agreed. Plastering and sealing around new frames is a common dispute; agree what is included.
• Zero-rating windows. Windows are not energy-saving materials for VAT, so they are standard-rated.
• Leaving out the due date. "Payment due within 14 days" or a date on the invoice gives you something to chase against. Without one, business customers default to 30 days.
• Losing track of what is unpaid. Chase on the day after the due date, not a month later; the guide to chasing an unpaid invoice has the wording.

Checklist before you send it

A quick check before sending saves a chase later:

• The invoice number is the next in your sequence and has never been used.
• The customer's name and address are right, with their purchase order or reference if they use one.
• Each line shows what was done, the quantity, the unit and the rate.
• The subtotal and total add up, and VAT appears only if you are VAT registered.
• The invoice date, a due date and your bank details are on it.
• A copy is saved with your records before you press send.

Keep a copy of every invoice

Your invoices are the evidence behind the income on your tax return, so keep a copy of every one. Making Tax Digital for Income Tax makes that digital: from 6 April 2026 for qualifying income over £50,000, from April 2027 over £30,000, and from April 2028 over £20,000, with quarterly updates to HMRC. Check your start date with the MTD requirement checker.

Download the window fitter invoice template

Download it as a Word document for Word or Google Docs, as an Excel workbook whose totals are live formulas, or as a print-ready PDF. Prefer to fill it in on screen? The free invoice generator opens pre-filled with the example window fitter lines, lets you choose a template and colour, and makes a finished PDF in a minute, with nothing stored.

For the tax side of the trade, from allowable expenses to Making Tax Digital, read the self-employed window fitter tax guide. A TapTax account, free to start, keeps your invoices and records together and files your quarterly updates to HMRC.