Company Car Fuel Benefit 2026/27: The Hidden Tax on "Free" Petrol

If your employer offers to pay for your private petrol as part of a company car package, it might sound like a generous perk. But in 2026/27, the tax charge on company car fuel benefit is substantial enough that accepting free fuel could cost you far more than the petrol is actually worth. This guide explains exactly how the charge works, how to calculate your personal tax bill, and how to decide whether opting out makes financial sense.

What Is Company Car Fuel Benefit?

When an employer pays for fuel that an employee uses for private journeys in a company car, HMRC treats this as a taxable benefit in kind (BiK). It does not matter how much or how little private fuel you actually use — if your employer offers to cover private fuel and you accept the arrangement, you are taxed on a fixed notional figure, not the actual cost of the petrol consumed.

This is the trap that catches many drivers off guard. Even if you drive only a handful of private miles per month, you are taxed as though you received the full benefit. The only way to escape this is to opt out entirely — making a formal declaration to your employer that you will pay for all private fuel yourself.

How the Fuel Benefit Charge Is Calculated

HMRC calculates your fuel benefit charge by multiplying two figures:

1. The fuel benefit multiplier — a fixed amount set each tax year (£27,800 for 2026/27)
2. Your car's BiK percentage — the same CO2-based rate used to calculate your company car benefit

So if your company car has a BiK percentage of 30% (a mid-range petrol car under current tables), your fuel benefit charge for 2026/27 is:

£27,800 × 30% = £8,340

This £8,340 is added to your taxable income. The actual income tax you pay on it depends on your marginal rate:

• Basic rate taxpayer (20%): £8,340 × 20% = £1,668 per year
• Higher rate taxpayer (40%): £8,340 × 40% = £3,336 per year
• Additional rate taxpayer (45%): £8,340 × 45% = £3,753 per year

Note that you also pay employee National Insurance on benefits in kind if they are processed via payroll, or the charge appears on your P11D and adjusts your tax code if they are not. Either way, the real cost is significant.

Real-World Examples for 2026/27

To see how this plays out in practice, consider three drivers with different company cars and income levels.

Example 1 — Basic rate taxpayer, low-emission petrol car (20% BiK)

Fuel benefit charge: £27,800 × 20% = £5,560 Income tax at 20%: £1,112 per year — roughly £93 per month

For this to break even, your employer would need to be paying for more than around £93 of private petrol per month. At current pump prices, that is roughly 70 to 80 litres of petrol per month for private use. Many commuters simply do not use that much.

Example 2 — Higher rate taxpayer, family SUV (33% BiK)

Fuel benefit charge: £27,800 × 33% = £9,174 Income tax at 40%: £3,670 per year — roughly £306 per month

To break even, your employer would need to fund well over £300 of private petrol every single month. For most people this is not achievable, making opt-out the obvious choice.

Example 3 — Higher rate taxpayer, hybrid car (12% BiK)

Fuel benefit charge: £27,800 × 12% = £3,336 Income tax at 40%: £1,334 per year — roughly £111 per month

Hybrids produce a lower BiK rate and therefore a lower fuel benefit charge. But even here, you need around £111 of employer-funded private petrol every month to come out ahead — still a high bar for most drivers.

Calculating Your Break-Even Point

The break-even calculation is straightforward. Work out your annual tax charge on the fuel benefit, then divide by 12 to get a monthly figure. This is the minimum value of private fuel your employer would need to provide for the benefit to be worth accepting.

Your annual tax charge = £27,800 × BiK% × your marginal tax rate

Then:

Monthly break-even = Annual tax charge ÷ 12

If your employer's fuel contribution for private use falls below this monthly figure, you will save money by opting out. If you are a higher-rate taxpayer with a typical petrol company car (around 25 to 35% BiK), the break-even point usually sits between £150 and £350 per month of private petrol — more than most drivers receive.

How to Opt Out and What Happens Next

Opting out of the fuel benefit is relatively straightforward but must be done correctly to be effective.

You should write to your employer stating that you will pay for all private fuel yourself from a specific date. Keep a copy of this communication. Your employer then has a legal obligation to stop funding your private fuel and to report on your P11D (or via payroll) that the fuel benefit ended on that date.

HMRC will adjust your tax code to remove the fuel benefit charge from that date onwards. If you opt out mid-year, the fuel benefit is pro-rated. So if you opt out on 5 October 2026 (halfway through the 2026/27 tax year), you will be charged for only approximately half the annual fuel benefit charge.

Critically, if you ever allow your employer to pay even a single penny of private fuel after opting out, the benefit reinstates for the entire tax year from the date of that payment. There is no partial reinstatement — it is all or nothing once you have opted out within a tax year.

Once you have opted out, you will need to track your business mileage carefully. Your employer can reimburse you tax-free at HMRC's Advisory Fuel Rates for business journeys in a company car. Keep accurate mileage logs showing dates, destinations, and business purpose.

Electric Cars: A Different Picture

If you drive a fully electric company car, the fuel benefit rules simply do not apply. HMRC does not treat electricity as a fuel for the purposes of the car fuel benefit charge. This means your employer can pay for your home or workplace charging without triggering any additional tax charge.

This is one of several reasons why the tax treatment of electric company cars remains significantly more attractive than petrol or diesel alternatives in 2026/27. The BiK rate for electric cars is just 3% in 2026/27, rising to 4% in 2027/28 and 5% in 2028/29 under current plans. Combined with no fuel benefit charge, the overall tax cost of an electric company car package is dramatically lower than an equivalent petrol vehicle.

Employer Perspective: Class 1A National Insurance

It is worth understanding that the fuel benefit costs your employer money too. Employers pay Class 1A National Insurance at 15% on all benefits in kind, including the fuel benefit charge.

Using the 30% BiK example above, where the fuel benefit charge is £8,340:

Employer Class 1A NI: £8,340 × 15% = £1,251 per year

This is on top of whatever the actual fuel costs your employer to provide. A larger employer with many company car drivers can face a substantial Class 1A NI liability on fuel benefits alone, which is one reason why some employers have already moved to electric fleets or eliminated fuel benefits altogether.

If you are negotiating your company car package, you may find your employer receptive to converting the fuel benefit into additional salary or other benefits that carry lower NI costs — a win for both sides.

Fuel Benefit vs Salary Sacrifice: Broader Context

The fuel benefit charge exists within a broader landscape of company car taxation. If you are considering your options, it is worth looking at salary sacrifice arrangements for electric vehicles, which remain highly tax-efficient in 2026/27 because the BiK rate on electric cars is so low.

Under a salary sacrifice arrangement for an EV, you give up gross salary in exchange for the car, reducing your income subject to income tax and National Insurance. With a 3% BiK rate and no fuel benefit charge, many employees find this dramatically cheaper than buying or financing a car privately.

uk-salary-sacrifice-explained-2026

Summary: Is Company Car Fuel Benefit Worth It in 2026/27?

For the vast majority of UK employees, company car fuel benefit is not worth having in 2026/27. The tax charge is calculated on a flat multiplier of £27,800 regardless of actual private mileage, which means low and moderate private drivers pay far more in tax than they receive in fuel. Higher-rate taxpayers in cars with mid-to-high BiK rates can face fuel benefit tax charges exceeding £3,000 per year.

The exception is drivers who genuinely use very high volumes of employer-funded private fuel — those putting in thousands of private miles per year where the employer pays at the pump. In those cases, it is still worth running the numbers, but such drivers are increasingly rare.

Electric car drivers face a different situation entirely: no fuel benefit charge applies, making employer-funded charging a genuinely valuable perk.

If you are currently receiving the fuel benefit and have not reviewed whether it is cost-effective, the start of a new tax year is the ideal time to do so. Opting out is permanent for the year once you do it, so make sure you are confident in your decision before you write to your employer.

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This article is for information only and does not constitute financial or tax advice. Tax rules may change. Consult a qualified adviser for your specific situation.