For many professionals, a company car is one of the most highly sought-after perks of a job. It offers convenience, saves on the upfront cost of vehicle ownership, and often includes insurance and maintenance. However, as the saying goes, “there is no such thing as a free lunch”, especially when His Majesty’s Revenue and Customs (HMRC) is involved. If you receive a company car that is available for private use, you will be liable to pay a specific type of tax known as Benefit in Kind (BiK).
In recent years, the landscape of BiK has undergone a massive transformation, largely driven by the global push toward sustainability and zero-emission vehicles. Understanding how BiK works, how it is calculated, and why electric vehicles (EVs) offer an unprecedented financial advantage is crucial for anyone considering a company car or a salary sacrifice scheme today.
Understanding Benefit in Kind (BiK)
Benefit in Kind is a tax levied on employees who receive perks or fringe benefits from their employer in addition to their standard salary. Because these benefits have a monetary value, HMRC considers them a form of income, and they are therefore subject to income tax.
BiK can apply to a wide variety of employer-provided perks, including private medical insurance, gym memberships, and non-business travel expenses. However, the most common and financially significant Benefit in Kind is the company car.
When an employer provides a vehicle that an employee can use outside of strictly business purposes—such as commuting to the office, running personal errands, or going on a weekend holiday—HMRC classifies this as a taxable benefit. The amount of tax you pay on this benefit is not arbitrary; it is calculated using a strict formula based on the vehicle’s characteristics and your personal financial situation.
How is Company Car BiK Calculated?
The amount of BiK tax you will pay for a company car depends on three primary factors:
- The P11D Value of the Vehicle: This is the list price of the car, including VAT and any optional extras or delivery charges, but excluding the first-year registration fee and vehicle tax. Even if your employer negotiated a massive fleet discount to buy the car, HMRC uses the official P11D list price for tax calculations.
- The BiK Rate (CO2 Emissions): This is a percentage determined by the car’s official carbon dioxide (CO2) emissions (measured in grams per kilometre) and its electric range. Vehicles that pollute more fall into higher BiK tax bands. This percentage can range from as low as 2% for zero-emission vehicles to a maximum cap of 37% for the most polluting petrol and diesel cars.
- Your Income Tax Bracket: The final variable is your personal income tax rate (e.g., 20% for basic rate taxpayers, 40% for higher rate, or 45% for additional rate taxpayers in the UK).
To calculate your annual company car tax, the following formula is used:
Annual Tax = (P11D Value × BiK Rate %) × Income Tax Bracket %
Your employer will usually deduct this tax directly from your monthly pay via the Pay As You Earn (PAYE) system by adjusting your tax code.
The Electric Advantage
If you are choosing a company car today, the single most important decision you will make is the fuel type. The UK Government uses the BiK tax system as a powerful lever to incentivize greener choices and penalize heavy polluters. Consequently, driving an Electric Vehicle (EV) is vastly more beneficial for your wallet than driving an Internal Combustion Engine (ICE) vehicle.
To encourage EV adoption, the government slashed BiK rates for pure electric vehicles to just 1% in the 2021/2022 tax year, rising to 2% for 2022 to 2025. Moving into the 2025/2026 tax year and beyond, the EV BiK rate is set to increase by just 1% annually (e.g., 3% in 25/26, 4% in 26/27, and 5% in 27/28). Even with these gradual increases, EV BiK rates remain astronomically lower than those of petrol or diesel cars.
Conversely, a standard petrol or diesel car easily hits BiK rates of 25% to 37%. Diesel cars that do not meet the strict RDE2 (Real Driving Emissions Step 2) standard are also subject to a 4% surcharge, pushing them to the maximum 37% cap even faster.
To truly understand the benefit, consider a higher-rate (40%) taxpayer choosing between a £40,000 petrol car and a £40,000 electric car for the 2026/2027 tax year, see below:
| Scenario A: Petrol Car (e.g., 140g/km CO2) | Scenario B: Pure Electric Car (0g/km CO2) |
| P11D Value: £40,000 | P11D Value: £40,000 |
| BiK Rate: 33% | BiK Rate: 4% (for 26/27 tax year) |
| Taxable Benefit Value: £40,000 × 0.33 = £13,200 | Taxable Benefit Value: £40,000 × 0.04 = £1,600 |
| Annual Tax Paid (at 40%): £13,200 × 0.40 = £5,280 per year (£440 per month) | Annual Tax Paid (at 40%): £1,600 × 0.40 = £640 per year (£53.33 per month) |
In this scenario, choosing the EV saves the driver almost £4,640 a year in tax alone.
Amplifying Savings with Salary Sacrifice
The low BiK rates for EVs have popularized “Salary Sacrifice” car schemes. In these schemes, an employee agrees to give up a portion of their gross salary in exchange for a fully maintained, insured, and taxed electric car.
Because the deduction is taken from your gross pay (before tax), you save on Income Tax and National Insurance Contributions (NICs) on that sacrificed amount. While you still have to pay the
BiK tax on the vehicle, the 2% to 5% BiK rate for EVs is so low that it is completely eclipsed by the massive Income Tax and NIC savings. If you tried to do this with a petrol car, the high BiK rate (up to 37%) would completely wipe out any tax savings from sacrificing your salary, making it financially unviable.
Conclusion
Benefit in Kind is a critical factor for any professional navigating the company car landscape. The days of choosing a vehicle based solely on brand prestige or horsepower are largely behind us.
Today, the tax implications dictate the smartest choice. By heavily discounting the BiK rates for zero-emission vehicles, the government has made driving an electric vehicle not just an environmental statement, but a profound financial advantage.
Whether through a traditional company car fleet or a modern salary sacrifice scheme, choosing an EV protects your take-home pay, slashes your monthly outgoings, and puts you behind the wheel of a newer, greener car for a fraction of the cost of its petrol equivalent.
