If your employer offers free fuel for private use in your company car, it might sound like a generous perk. In practice, the fuel benefit charge for 2026/27 makes this one of the most expensive Benefit in Kind traps for employees. The car fuel benefit multiplier is £29,200, and for most drivers the tax bill far exceeds the value of the fuel they actually use. Here is exactly how it works and what you can do about it.
How the Fuel Benefit Charge Is Calculated
HMRC sets a fixed fuel benefit multiplier each tax year. For 2026/27 the car fuel benefit multiplier is £29,200. This figure does not change based on how much private fuel you use, how efficient your car is, or what type of fuel it runs on. It is a flat charge.
The calculation is straightforward:
Fuel benefit taxable amount = £29,200 × your car’s CO2 BIK percentage
You then pay income tax on that taxable amount at your marginal rate.
Worked example — petrol car, 128 g/km CO2 (32% BIK)
- Taxable fuel benefit: £29,200 × 32% = £9,344
- Higher-rate taxpayer (40%): £9,344 × 40% = £3,738 per year (£311 per month)
- Basic-rate taxpayer (20%): £9,344 × 20% = £1,869 per year (£156 per month)
For the higher-rate taxpayer to break even, they would need to consume at least £3,738 of free fuel on private journeys. At roughly 14p per mile in fuel costs, that is around 26,700 private miles per year — far more than most company car drivers cover privately.
For the full BIK percentage table and how your car’s CO2 band is determined, see our company car tax 2026 BIK rates guide.
Why Even One Litre of Private Fuel Triggers the Full Charge
This is the detail that catches many employees off guard. The fuel benefit charge is all or nothing. If your employer pays for any fuel used for private journeys — including your daily commute — the full annual charge applies.
There is no pro-rata reduction based on how much private fuel you actually use. One tank of fuel paid by your employer for a weekend trip triggers the same £29,200 multiplier as if they paid for every private mile all year.
The only exception is if the fuel benefit arrangement is formally withdrawn partway through the tax year. In that case, the charge is proportioned to the number of complete tax months (rounded down) the benefit was available. But sporadic or occasional use does not reduce the charge — it must be a clean, documented withdrawal.
This all-or-nothing structure is deliberate. HMRC designed the fuel benefit charge to discourage employers from providing free private fuel, and it works: most employees are better off refusing the perk entirely.
Van Fuel Benefit Charge for 2026/27
If you drive a company van rather than a car, the fuel benefit charge works differently. Instead of the £29,200 multiplier applied to a CO2 percentage, the van fuel benefit is a flat £798 for 2026/27.
You pay income tax on that £798 at your marginal rate:
- Basic-rate taxpayer: £798 × 20% = £160 per year
- Higher-rate taxpayer: £798 × 40% = £319 per year
This is considerably cheaper than the car fuel benefit, and for van drivers who do significant private mileage, accepting free fuel may actually make financial sense. For more on van BIK generally, see our company van benefit in kind 2026 guide.
How to Avoid the Fuel Benefit Charge
The most reliable way to avoid the charge is simple: pay for all your private fuel yourself. If you never use your employer’s fuel card or account for private mileage, no fuel benefit charge arises.
In practice, many employees use a company fuel card for both business and private journeys. To avoid the fuel benefit charge in this scenario, you must reimburse your employer for the private portion. This requires accurate records of which journeys were business and which were private.
Tripbook makes this straightforward. The app automatically logs every journey with GPS tracking, and you categorise each trip as business or personal. At the end of each month, you have a clear record of your private mileage, making it simple to calculate the reimbursement owed to your employer.
HMRC advisory fuel rates provide a per-mile rate that employers can use to calculate reimbursement for private fuel. These rates are updated quarterly and vary by engine size and fuel type. Using advisory fuel rates removes any argument about how much private fuel cost — see our HMRC advisory fuel rates 2026 guide for the current figures.
The key steps to avoid the charge:
- Track every journey — log business and private trips separately using Tripbook
- Reimburse private fuel — calculate private mileage × advisory fuel rate and repay your employer monthly
- Keep records — HMRC may ask for evidence that private fuel was fully reimbursed; your Tripbook mileage log provides this
If you reimburse all private fuel by the deadline (6 July following the end of the tax year for P11D purposes), no fuel benefit charge is reported.
Employer Costs: Class 1A National Insurance on Fuel Benefit
The fuel benefit charge does not just affect the employee. The employer must pay Class 1A National Insurance contributions at 13.8% on the fuel benefit amount.
Using the earlier example (£9,344 fuel benefit at 32% BIK):
- Employer Class 1A NIC: £9,344 × 13.8% = £1,289 per year
This is on top of the Class 1A NIC the employer already pays on the car benefit itself. For employers providing free fuel across a fleet of company cars, these costs add up quickly. Many employers have stopped offering free private fuel for precisely this reason — the combined employee tax and employer NIC make it poor value for both parties.
Employers report the fuel benefit on the employee’s P11D form. For details on how this reporting works, see our P11D company car reporting 2026 guide.
Electric Cars and the Fuel Benefit Charge
There is no fuel benefit charge when an employer provides electricity for private use of a company electric vehicle. Free workplace charging or a charge card for an EV does not trigger a taxable benefit.
This is one of the most significant advantages of choosing an electric company car. Combined with the ultra-low 3% BIK rate for zero-emission vehicles in 2026/27, company EVs remain exceptionally tax-efficient compared to petrol or diesel alternatives.
The advisory electricity rate (AER) for reimbursing employees who charge their EV at home for business journeys is separate from the fuel benefit question — it applies when the employee pays for electricity, not the employer.
Should You Accept Free Private Fuel?
For most company car drivers, the answer is no. The fuel benefit charge for 2026/27 based on the £29,200 multiplier makes free private fuel a losing proposition unless you drive an exceptionally high number of private miles in a low-emission vehicle.
The break-even calculation is simple: if the tax you pay on the fuel benefit exceeds the cost of buying your own private fuel, you are better off declining the perk. For the vast majority of employees — particularly higher-rate taxpayers with mid-to-high emission cars — paying for your own fuel and keeping accurate mileage records with Tripbook saves money every month.
Download Tripbook from the App Store to start logging your business and private mileage automatically.
