Capital Allowances on Cars and Vehicles: The CO2 Decision for UK Businesses

How a vehicle is taxed as a capital asset is decided almost entirely before you drive it off the forecourt. Two businesses can spend exactly the same money in the same month and end up with wildly different tax outcomes, because the relief on a car follows its CO2 emissions and its classification, not its price. A new electric car can hand you the full cost as a deduction in year one. An otherwise similar petrol car can take more than a decade to give you the same relief. This page is the buying decision, not the bookkeeping. For the reducing-balance pool arithmetic once the car is in your accounts, we link up to the full mechanics below.

Why cars follow different rules from every other business asset

Most business equipment is generous to buy. A laptop, a machine, a set of tools: all are plant and machinery, all qualify for the Annual Investment Allowance (up to £1 million a year) or full expensing, and all can normally be deducted in full against profit in the year you buy them. Cars are the deliberate exception.

Cars are excluded from the Annual Investment Allowance (CAA 2001 s.38B), excluded from full expensing, and excluded from the 40% first-year allowance introduced for main-pool plant in 2026. HM Revenue and Customs takes this position because a car nearly always carries an element of private benefit, and the tax system does not want to hand a full and immediate write-off for an asset the owner also drives to the supermarket. The result is that a car normally gives up its relief slowly, over many years, at either 14% or 6% a year on a reducing balance.

There is exactly one exception that restores a 100% deduction, and it is the reason the CO2 figure matters so much. We come to it next.

The three routes a car can take

Every car your business buys lands in one of three places, and the CO2 emissions figure on the V5C decides which:

• 100% first-year allowance · new and unused cars with CO2 emissions of exactly 0g/km (fully electric or hydrogen). The entire cost is deducted in year one under CAA 2001 s.45D.
• Main pool, 14% a year · cars with CO2 emissions of 50g/km or less that do not qualify for the first-year allowance, including all second-hand electric cars. Written down at 14% on the reducing balance from April 2026 (it was 18% before).
• Special rate pool, 6% a year · cars with CO2 emissions above 50g/km. Written down at just 6% on the reducing balance.

To see why this is a decision and not a detail, take a business spending £45,000 on a car.

£45,000 car	New electric (0g/km)	Petrol (over 50g/km)
Route	100% first-year allowance	Special rate pool, 6%
Year-one deduction	£45,000	£2,700
Year-one Corporation Tax saved (25%)	£11,250	£675
Cost still unrelieved after year one	£0	£42,300

Same £45,000, same day, same company. The electric car frees up £11,250 of tax in year one. The petrol car frees up £675 and then dribbles out the remaining relief at 6% of a shrinking balance, taking well over a decade to catch up. The gap is not a rounding difference. It is the entire point of the regime, and it is fixed the moment you choose the vehicle.

Electric and zero-emission cars: the 100% allowance in detail

The 100% first-year allowance under s.45D is the single most valuable feature of the car rules, and it is also the easiest to lose on a technicality. Three conditions all have to be met:

• Zero emissions · the car must emit 0g/km of CO2. Not low. Zero. A plug-in hybrid at 20g/km does not qualify, however green the marketing.
• New and unused · a pre-registered, ex-demo or second-hand electric car fails this test and drops into the main pool at 14% instead. The saving on a used electric car is far smaller than most buyers expect.
• Bought, not leased · the allowance is for capital expenditure, so it applies where you buy the car outright or on hire purchase, not where you take it on an operating lease.

The relief is time-limited. It is currently legislated to run for expenditure up to 31 March 2027 for Corporation Tax and 5 April 2027 for Income Tax, having been extended several times rather than made permanent. Because the difference between claiming and missing it can be the full purchase price as a deduction, treat the end date as a live figure and confirm it is still in force for your delivery date before you order. Verify the current date at the time you read this.

Vans, pickups and lorries: plant, not cars

The car rules only bite on cars. A vehicle that is not a car for tax purposes is ordinary plant and machinery, which means it does qualify for the Annual Investment Allowance and full expensing and can usually be written off in full in the year of purchase. That covers most vans, lorries, HGVs and genuine commercial vehicles.

Zero-emission vans get their own 100% first-year allowance under CAA 2001 s.45DA, and even a diesel van typically clears its full cost through the Annual Investment Allowance. So a business choosing between a car and a van for the same role is often choosing between slow relief and immediate relief.

Double-cab pickups are the well-known trap. Following changes taking effect from April 2025, HMRC treats most double-cab pickups with a payload of one tonne or more as cars for capital allowances and benefit-in-kind purposes, which removes access to the Annual Investment Allowance and pushes them into the CO2-based pools. Transitional rules protect vehicles that were bought, leased or ordered before the change, so the acquisition date is decisive. If a pickup is central to your plan, check its status against the current rules rather than assuming the older van treatment still applies.

Cars versus vans: why the classification is the decision

Because a van gets the Annual Investment Allowance and a car does not, the classification question is worth more than almost any other single point on this page. HMRC and the courts look at the vehicle's construction and primary suitability, not the name on the brochure. A vehicle built primarily to carry goods is generally a van; a vehicle built primarily to carry passengers is a car, even if it has a large boot.

The practical upshot for a buyer: if a genuine commercial vehicle can do the job, the year-one relief is dramatically better than the equivalent car, and there is no CO2 penalty on the timing. If only a car will do, the decision collapses back to the CO2 band and the new-versus-used electric question. Getting the classification wrong in either direction, treating a car as a van or missing that a pickup is now a car, is one of the more common and expensive errors HMRC picks up on enquiry.

Leased versus bought: the emissions penalty follows you

Capital allowances only apply to assets you own, so a car on an operating lease attracts no allowances at all. Instead you deduct the lease rentals as a business running cost. That does not make leasing a way around the CO2 rules, because the emissions penalty simply moves.

For a leased car emitting more than 50g/km, a flat 15% of the lease rental is permanently disallowed for tax. So a high-emission car costs you more whether you buy it (special rate pool at 6%) or lease it (15% of the rental lost). A zero-emission leased car escapes the 15% restriction entirely, mirroring the advantage a bought electric car gets from the first-year allowance. Whichever route you take, the low-emission choice is the tax-efficient one; leasing does not rescue a high-emission car.

Disposals and balancing adjustments

When you sell or stop using a business car, you bring in a disposal value, normally the sale proceeds. What happens next depends on how the car was pooled, and this is where we defer to the full mechanics. In short: a car held in a single-asset pool (typically because of private use) produces a balancing allowance or a balancing charge on disposal, comparing the sale value with the written-down balance. A car in the general main or special rate pool simply reduces the pool balance, so no separate balancing event usually arises. A zero-emission car that took the 100% first-year allowance has effectively been fully relieved, so the sale proceeds are typically clawed straight back as a balancing charge; the allowance was a timing benefit, not a permanent one.

The reducing-balance calculations, the April 2026 rate change from 18% to 14%, the single-asset pool mechanics and the interaction with simplified mileage rates are all covered in detail on our writing down allowance on cars guide. This page is the buying decision; that page is the arithmetic once the car is in your books.

Getting the decision right before you buy

For a single car, the rules on this page usually settle it: choose zero emissions and new if you want the money back this year, treat anything over 50g/km as a slow write-off, and check whether a genuine van would do the job for full immediate relief. The complexity arrives when the decision scales up.

A fleet, a mix of cars and vans, a salary-sacrifice scheme, a high-value purchase timed near a fiscal-event deadline, or a double-cab pickup near the classification line all reward a proper whole-life tax model rather than a forecourt guess. Capital allowances on vehicles also sit alongside benefit-in-kind charges, VAT recovery and the wider capital allowances position on your commercial property, and the tax-efficient answer for the business is not always the one that looks cheapest on the invoice.

If you want the full commercial capital allowances picture, our embedded capital allowances in commercial property guide covers the fixtures and integral features hidden in a building, our full expensing and first-year allowances guide explains which first-year relief applies to non-car plant, and you can size a claim with our capital allowances calculator.

Authoritative sources

The rules on this page are set out in primary legislation and HMRC's own manuals. For the qualifying conditions and rates, see:

• CAA 2001 s.45D, the 100% first-year allowance for low-emission cars, and s.45DA for zero-emission goods vehicles (legislation.gov.uk).
• CAA 2001 s.104A and s.104AA, the special rate pool covering higher-emission cars (legislation.gov.uk).
• HMRC Capital Allowances Manual CA23153, first-year allowances and the CO2 thresholds for cars (gov.uk).
• HMRC Capital Allowances Manual CA23155, the meaning of a car and the first-year allowance conditions (gov.uk).
• gov.uk, "Claim capital allowances: business cars", for the current CO2 bands and rates in plain terms (gov.uk).

Tax rates, CO2 thresholds and the first-year allowance end date are reviewed at successive fiscal events. The figures here reflect the position for 2026/27; confirm the current rules before you rely on them for a purchase.