HVAC engineer invoice template: installs, servicing, CIS and VAT
An air conditioning or ventilation engineer can do three jobs in a week that HMRC treats three different ways: a new system on a fit-out (inside CIS), a service visit (outside CIS) and a split unit in someone's home (possibly 0% VAT). This guide shows how to invoice each one, with checked figures.
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HVAC and air conditioning rates
Checkatrade's air conditioner installation cost guide (updated August 2026) says air conditioning engineers typically charge £280 to £720 a day, with labour to install a wall-mounted split unit averaging about £960 to £1,380 per unit and a one-off service about £70 to £120 per unit. These are prices homeowners pay. Commercial subcontract rates are agreed per job or per day with the contractor, and the range is wide because it depends on the system, your F-gas category and whether you bring a mate.
For installs, quote per system, with the units, pipework, electrics and making good priced separately. For a homeowner, the free quote generator makes a PDF quote with labour and materials on separate lines, and with an account you can save it and turn it into the invoice when the job's done. To check your day rate covers your van, tools and recovery equipment, use the day rate calculator.
What goes on an HVAC invoice
- The site and system ("3 × wall-mounted split units, 2nd floor offices").
- Labour by day or as the quoted install price.
- Units and materials you supplied: indoor and outdoor units, refrigerant pipe, cable, brackets, condensate pumps, refrigerant charged. Put them on their own lines.
- Commissioning and handover, and the F-gas details your customer needs for their records (refrigerant type and amount added). Keep the legal record-keeping separate from the invoice, but a reference on the invoice helps.
- Electrical work: if a separate electrician did the supply, show it as their line or let them invoice directly.
CIS: installation is in, servicing and repairs usually aren't
HMRC's manual CISR14090 says installing a system of heating, air conditioning or ventilation in a building is a construction operation. It also says the rule covers installation only, not repair or maintenance, and not altering or extending an existing system, while replacing a whole system counts as installing one. In practice:
- New system or full replacement for a contractor: inside CIS. The contractor deducts 20% (registered), 30% (unregistered) or nothing (gross payment status) from your labour.
- Servicing, regas, swapping a fan motor or a PCB: outside CIS on its own. But HMRC notes that if a repair contract includes making good to the building, it can be caught, so say so on the invoice when it doesn't.
- Built-in refrigeration such as cold stores, installed as part of a construction project, is inside CIS (CISR14240). Free-standing fridges aren't.
- Homeowners: never CIS.
Adding units to an existing system for a contractor is an extension, which CISR14090 says isn't covered on its own. Where it's part of a wider fit-out, the whole contract may still be in, so check with the contractor, HMRC or your accountant if it isn't clear.
Worked example: an office fit-out and a service visit
Marcus installs a new air conditioning system in an office fit-out for a contractor, who supplied the units. Marcus is CIS registered (20%) and VAT registered. The day rate is an illustration inside the Checkatrade range.
| Line | Qty | Rate | Amount |
|---|---|---|---|
| Install and commission 3 split units, 2nd floor (labour) | 4 days | £380.00 | £1,520.00 |
| Refrigerant pipe, cable, brackets and condensate pumps bought by Marcus (materials) | 1 | £486.40 | £486.40 |
| Net total | £2,006.40 |
| Labour subject to CIS | £1,520.00 |
| CIS deduction at 20% | £304.00 |
| Paid to Marcus | £1,702.40 |
Check: 4 × £380 = £1,520. 20% of that is £304. £2,006.40 − £304.00 = £1,702.40. The contractor is VAT and CIS registered and this is standard-rated commercial work, so the invoice is under the domestic reverse charge: no VAT is added, it says "Reverse charge: Customer to pay the VAT to HMRC", and shows the VAT for information (20% of £2,006.40 = £401.28).
The next week Marcus services two units for a shop owner. That's maintenance, not installation, so there's no CIS and no reverse charge:
| Service 2 wall-mounted units (labour, 3 hours at £55.00) | £165.00 |
| Refrigerant top-up (materials) | £48.00 |
| Net | £213.00 |
| VAT at 20% | £42.60 |
| Total due | £255.60 |
Check: £165 + £48 = £213; 20% of £213 is £42.60.
VAT: when air con in a home can be 0%
Air source heat pumps installed in residential accommodation are energy-saving materials, zero rated until 31 March 2027. VAT Notice 708/6 (section 2.15) says only permanently fixed units qualify, not portable ones, and that HMRC's understanding is that most air conditioning units are air source heat pumps, but in cases of doubt it depends on the facts of each case. So a fixed split unit in a home can usually be zero rated if you're VAT registered. If you're unsure whether a product qualifies, check with HMRC or your accountant before invoicing at 0%.
Commercial work (offices, shops) is standard rated, with the reverse charge where the customer is a VAT and CIS-registered contractor. Servicing and repairs are standard rated.
Common mistakes
- Letting a contractor take CIS off service and repair visits. Those are normally outside CIS.
- Charging 20% VAT on a fixed unit in a home without checking whether it qualifies for 0%.
- Zero rating a portable unit. Only permanently fixed units can qualify.
- Putting units the contractor supplied on your invoice.
- Missing the refrigerant details the customer needs for their F-gas records.
Free HVAC invoice template
For contractor installs, download the free CIS invoice template (PDF or Excel). For service visits and homeowner jobs, use the general invoice template (PDF, Word or Excel). Neither is HVAC-specific. See reverse charge and CIS wording on the sample invoice. If CIS is taken off your pay, the CIS refund checker gives a quick estimate (not tax advice) of whether you may be due money back.
Related trade guides
HVAC work overlaps with the electrician (supplies and isolators), the gas engineer (heating systems and heat pumps) and the plumber. See all trade invoicing guides.
Free: The UK Contractor's Cheat Sheet 2026/27
CIS rates, overtime maths, tax dates, mileage, VAT and late payment, on 2 pages. Keep it on your phone or print it for the van.
Frequently asked questions
Does CIS apply to air conditioning installation?
Yes, installing an air conditioning or ventilation system in a building for a contractor is inside CIS. Repairs and maintenance on their own are not, and nor is altering or extending an existing system on its own.
Is air conditioning zero rated for VAT?
It can be. HMRC says most air conditioning units are air source heat pumps, and a permanently fixed one installed in a home is zero rated until 31 March 2027. In cases of doubt it depends on the facts, so check before invoicing at 0%.
Is servicing air con reverse charged?
No. Servicing isn't construction work for CIS, so the reverse charge doesn't apply. Charge VAT in the normal way if you're registered.
Should I show the refrigerant on the invoice?
It's sensible to show the refrigerant added as its own line, and to give the customer the details they need for their own F-gas records.
Sources
- Construction Industry Scheme manual CISR14090: building service systems – HMRC
- Construction Industry Scheme manual CISR14240: preparatory, integral and finishing operations – HMRC
- VAT Notice 708/6: energy-saving materials and heating equipment (section 2.15, air source heat pumps) – GOV.UK
- VAT reverse charge technical guide – GOV.UK
- Air conditioner installation: cost breakdown 2026 (updated August 2026) – Checkatrade
This guide is general information, not legal, tax or financial advice. Rules and rates change, so check the linked GOV.UK pages for the current position.