Car benefit tax is the income tax you pay when your employer gives you a car you can use for personal journeys. HMRC treats that private-use car as a benefit in kind, adding a notional value to your earnings even though no cash reaches your account. The bill depends on three numbers: the car’s list price, its CO₂ emissions, and your marginal income tax rate. For 2025/26, the benefit in kind percentage runs from 3% for a pure electric car up to a capped 37% for the highest-emission vehicles.1GOV.UK. Work Out the Appropriate Percentage for Company Car Benefits (480: Appendix 2)
When You Owe the Tax
The charge applies as soon as the car is made available for your private use, not when you actually drive it privately.2legislation.gov.uk. Income Tax (Earnings and Pensions) Act 2003 – Section 114 If the car sits on your driveway all weekend and never moves, HMRC still considers it available and the tax still applies. Directors and employees are treated the same way. If the car is provided by reason of your employment and you can use it privately, you pay.3GOV.UK. Tax on Company Benefits – Tax on Company Cars
The most common surprise is commuting. HMRC treats travel between your home and your permanent workplace as ordinary commuting, not business travel.4GOV.UK. Ordinary Commuting and Private Travel (490: Chapter 3) Even if you only ever use the car to reach the office, that is private use, and the full benefit charge stands. Travel to a temporary workplace, such as a client site you visit for a fixed project, does count as business.
How Car Benefit Tax Is Calculated
Three steps. Each feeds the next.
Step 1: The P11D Value
Start with the car’s P11D value: its list price including VAT, delivery charges, and any optional extras fitted before it was first made available to you. Upgraded alloys, premium paint, an improved sound system — those all get added.5GOV.UK. How to Work Out the Benefit of a Company Car (480: Chapter 12) What your employer actually paid is irrelevant. Fleet discounts don’t reduce the figure. HMRC uses the manufacturer’s list price.
Step 2: The BIK Percentage
Multiply the P11D value by the benefit in kind percentage set by the car’s CO₂ emissions. Lower emissions, lower percentage, lower tax. A pure electric car sits at 3%; a petrol car emitting 155 g/km or more hits the 37% ceiling.1GOV.UK. Work Out the Appropriate Percentage for Company Car Benefits (480: Appendix 2) The result is your taxable benefit — the amount added to your income for the year.
Step 3: Your Marginal Rate
You then pay income tax on the taxable benefit at your marginal rate. In England, Wales, and Northern Ireland for 2025/26, that’s 20% at the basic rate and 40% at the higher rate.6GOV.UK. Income Tax Rates and Allowances for Current and Previous Tax Years
A Worked Example
Say your employer provides a petrol car with a P11D value of £30,000, and its emissions place it in the 25% band. Your taxable benefit is £7,500. A basic rate taxpayer pays 20% of that, so £1,500 a year. A higher rate taxpayer pays 40%, so £3,000 a year for the same car.5GOV.UK. How to Work Out the Benefit of a Company Car (480: Chapter 12)
BIK Rates for 2025/26
The percentage table is where the real choices happen. Dropping one emissions band can save hundreds a year, and the electric versus petrol gap is dramatic. Key figures for 2025/26:1GOV.UK. Work Out the Appropriate Percentage for Company Car Benefits (480: Appendix 2)
- 0 g/km (pure electric): 3%
- 1–50 g/km, 130+ miles electric range: 3%
- 1–50 g/km, 70–129 miles electric range: 6%
- 1–50 g/km, 40–69 miles electric range: 9%
- 1–50 g/km, 30–39 miles electric range: 13%
- 1–50 g/km, under 30 miles electric range: 15%
- 51–54 g/km: 16%
- 75–79 g/km: 21%
- 100–104 g/km: 26%
- 125–129 g/km: 31%
- 155 g/km and above: 37% (the maximum)
The scale of the gap matters. A £40,000 electric car at 3% produces a £1,200 taxable benefit, costing a basic rate taxpayer £240 a year. The same car with a petrol engine emitting 130 g/km sits in the 32% band, giving a £12,800 taxable benefit and £2,560 of tax for the same person. More than ten times the bill for the petrol version.
The Diesel Supplement
Diesel cars that don’t meet the Real Driving Emissions 2 (RDE2) standard for nitrogen oxide face a 4% surcharge on top of the standard BIK percentage. A diesel in the 25% band becomes 29%, though the combined figure is still capped at 37%. Most diesels registered from September 2017 onward meet RDE2, but older models and some budget options may not. Worth asking before you sign.
Car Fuel Benefit
If your employer also pays for fuel you use on private journeys — through a fuel card, receipt reimbursement, or filling the tank directly — there is a separate charge on top of the car benefit itself. Car fuel benefit is calculated by applying the same BIK percentage to a fixed multiplier that HMRC sets each tax year.
The charge is all or nothing. Unless you reimburse your employer for every drop of private fuel, the full benefit applies no matter how little private mileage you actually do. For many employees, especially those with limited private driving, declining the fuel benefit and paying for personal fuel yourself works out cheaper.
How the Tax Reaches Your Payslip
Your employer does the reporting. The traditional route is the P11D form, submitted after the tax year ends for every employee who received a taxable benefit.7GOV.UK. Expenses and Benefits for Employers: Reporting and Paying It captures the car’s details, P11D value, CO₂ emissions, fuel type, and dates of availability.
Employers can also payroll the benefit, accounting for the taxable value through regular payroll throughout the year instead of filing a P11D afterwards. This spreads the tax collection evenly and avoids retrospective tax code adjustments.
Either way, the tax comes out through PAYE. HMRC lowers your tax code to reflect the extra income from the car, which reduces your tax-free pay each month. You’ll usually see this as a lower tax code — dropping from 1257L to something smaller — and a corresponding cut in take-home pay.3GOV.UK. Tax on Company Benefits – Tax on Company Cars
Pool Cars: The One Real Exemption
A genuine pool car generates no taxable benefit at all, but qualifying is harder than most people assume. Section 167 of the Income Tax (Earnings and Pensions) Act 2003 sets five conditions, and every one must be met:8legislation.gov.uk. Income Tax (Earnings and Pensions) Act 2003 – Section 167
- The car is available to, and actually used by, more than one employee.
- It is not ordinarily used by one person to the exclusion of others.
- Any private use is merely incidental to business use.
- It is not normally kept overnight at or near an employee’s home, unless on the employer’s premises.
- It is made available to each user by reason of their employment.
Meeting four conditions and narrowly failing the fifth means the car fails entirely.9GOV.UK. EIM23450 – Car and Van Benefit: Pooled Cars and Vans: General The overnight rule catches most employers out. If one employee regularly takes the car home the night before an early meeting, that pattern can disqualify the whole arrangement and pull everyone who used the car back into the standard charge.
Electric Vehicles and What Comes Next
The 3% rate for pure electric cars is the biggest incentive in the company car system right now. For someone choosing between a petrol car and an electric car of similar list price, the annual tax difference easily runs into thousands of pounds. That is why electric vehicles have dominated new company car registrations in recent years.
The government has confirmed that BIK rates for electric vehicles will rise gradually in future tax years, so the gap between electric and conventional cars will narrow. Employees choosing an electric car now keep the current rate for the duration of their lease or arrangement, which makes the timing of the decision a real financial factor rather than an afterthought.