Air Conditioning & Capital Allowances for Businesses
Air conditioning is one of the larger capital purchases a small or medium business makes for its premises, and most of the cost can be set against tax — usually in the year you buy it. This guide explains in plain terms how the Annual Investment Allowance, full expensing, first-year allowances and writing-down allowances apply to air conditioning, what counts as an integral feature, and what records to keep. General guidance, not tax advice: confirm the figures and your position with your accountant.
Which allowance applies to air conditioning
Four routes; which one your spend takes depends on your structure, how much you have invested that year and whether the equipment is new.
| Relief | Who can use it | Rate on air conditioning | Notes (2026 — verify current figures) |
|---|---|---|---|
| Annual Investment Allowance (AIA) | Companies, sole traders, partnerships | 100% in year of purchase | Cap of £1 million a year across all qualifying plant; covers special-rate integral features; new or second-hand |
| Full expensing | Companies only | Not 100% — air con is special-rate | 100% applies to new main-rate plant; integral features use the 50% allowance below |
| 50% first-year allowance (special rate) | Companies only | 50% in year one, balance into special-rate pool | New and unused assets; useful where AIA is already used up |
| Writing-down allowance (special-rate pool) | Everyone | 6% a year, reducing balance | The default where no first-year relief is claimed; very slow |
Capital Allowances Act 2001 as amended; AIA cap and permanent full expensing confirmed at recent Budgets. Check current rates on GOV.UK or with an accountant before relying on them.
Why air conditioning is an "integral feature"
The legislation lists specific building systems as integral features: electrical and lighting, cold water, space or water heating, powered ventilation, air cooling or air purification, lifts and escalators, and external solar shading. Air conditioning sits squarely in "air cooling systems", which means two things: it is plant and machinery even though it is fixed to the building, so it qualifies at all; and it is special-rate, so without the AIA or the 50% first-year allowance it would be written down at only 6% a year. Pipework, ducting, condensers, controls and installation labour are all qualifying cost; general building works such as new ceilings or redecoration usually are not — which is why an itemised invoice matters.
A worked illustration
A limited company fits a small VRF system of roughly 40 kW in its office. At the 2026 baseline of £350–£600 per kW that is £14,000–£24,000; take £20,000 as a round figure. Purely to show the mechanics — your accountant applies your actual rates and circumstances:
| Route | Year-one deduction from profits | What happens to the rest |
|---|---|---|
| AIA (cap not exceeded) | £20,000 | Nothing left to claim |
| 50% special-rate FYA (AIA used up) | £10,000 | £10,000 into the special-rate pool at 6% a year |
| Special-rate WDA only | £1,200 | Balance written down at 6% a year |
Tax saved equals the deduction multiplied by your marginal rate of corporation or income tax. Installation figure from our VRF guide; allowance mechanics simplified.
Points to raise with your accountant
- Timing — allowances are claimed for the period in which the spend is incurred, so an install completed just before year-end brings relief forward.
- Own versus lease — tenants can usually claim on air conditioning they pay for; check the lease for who owns the fixtures at the end of the term.
- Finance — hire-purchase normally preserves your claim; operating leases and rental generally shift it to the lessor.
- Repairs versus improvements — maintenance and repairs are revenue costs deducted as you go; see maintenance contracts.
For what a system is likely to cost before relief, start with the commercial air conditioning cost guide and the office fit-out guide (£150–£300 per m²).
Sources & methodology
- Capital Allowances Act 2001 (ss. 33A–33B integral features; Part 2 plant and machinery); HMRC Capital Allowances Manual.
FAQs
Price the system before you talk to your accountant
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