Gas engineer
invoice template

Gas engineers invoice homeowners, landlords and letting agents for boiler installations, annual services, repairs and landlord gas safety records. Below is a ready-made gas engineer 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 gas engineer invoice

Describe the appliance and the work (annual service, combi boiler; replace diverter valve; landlord gas safety record, 3 appliances), list parts with their names, and include your Gas Safe registration number and the certificate or record number.

Line by line: Landlord gas safety record, 3 appliances, 1 × £85.00 = £85.00; Boiler service, 1 × £90.00 = £90.00; Replace diverter valve, parts and labour, 1 job × £240.00 = £240.00. The subtotal is £415.00. The example assumes you are not VAT registered, so there is no VAT and the total due is £415.00. 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 gas engineers; 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 gas engineers price their work

Services and safety records are fixed fees; repairs are call-out plus parts and labour; installations are quoted as fixed prices, often with a longer manufacturer's warranty.

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 the appliances covered, what a service includes, the price of parts found necessary, access for tenants on landlord jobs, and who pays for a failed safety check's remedial work.

When to send a gas engineer invoice

Services and safety records on the day; repairs on completion; installations with a deposit and balance on commissioning.

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 gas engineer invoices

Boiler replacement and gas repairs are standard-rated: a gas boiler is not an energy-saving material. Grant-funded heating installed for qualifying people, such as those on certain benefits or aged 60 or over, can be charged at 5%.

Once registered, gas engineers charge 20% on most work. Two reliefs come up often: the zero rate for installing qualifying energy-saving materials in residential homes, which runs until 31 March 2027, and the zero rate for work on a new dwelling. VAT Notice 708/6 lists which materials qualify, and anything outside the list is standard-rated.

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

CIS covers the installation of systems in buildings, so it applies whenever a contractor pays you for that work. The deduction comes off the labour only, at 20% when you are registered, which is why the invoice shows materials separately. HMRC's CIS 340 guide is explicit that repairing, servicing or maintaining a system, or replacing parts of one, is not an installation and falls outside the scheme. Jobs for a householder are outside CIS entirely: a homeowner is never a contractor.

By law, gas work must be done by a Gas Safe registered engineer; your registration number on the invoice reassures customers and letting agents.

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 on boiler installations are common; services and repairs are paid on the day.

Ask for a deposit when you have to buy equipment for a specific customer, and invoice the balance once the system is commissioned and handed over. Small repairs are simplest paid on the day, by card or bank transfer, with the invoice sent before you leave.

Payment terms for gas engineers

Letting agents usually pay within 14 or 30 days; homeowners on the day.

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 gas engineer invoicing mistakes

• Missing the gas safety record number. Agents need it to show the landlord met the annual check.
• Parts named vaguely. "Parts" invites questions; name the component.
• Charging 5% without checking eligibility. Keep evidence that the grant-funded conditions are met.
• 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 gas engineer 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 gas engineer 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 gas engineer tax guide. A TapTax account, free to start, keeps your invoices and records together and files your quarterly updates to HMRC.