Company Car Tax Calculator
Use this calculator to estimate your annual and monthly company car tax cost based on a Benefit-in-Kind (BIK) approach.
Optional: quick BIK starter estimate
What is company car tax?
Company car tax is the income tax you pay when your employer provides a car that you can use personally (not just for business travel). In many systems, including the UK model, this is treated as a Benefit in Kind (BIK). That means the value of the car benefit is added to your taxable income.
Your final tax bill is mainly driven by three numbers:
- P11D value (list price): the taxable value basis of the car.
- BIK percentage: a tax percentage usually based on emissions/fuel type and tax year.
- Your personal tax rate: for example 20%, 40%, or 45%.
How this company car calculator works
The calculator follows a straightforward estimate formula:
- Taxable car benefit = (List Price × BIK%) − Employee Contribution
- Annual car tax = Taxable car benefit × Personal tax rate
- Fuel benefit tax (optional) = Fuel Multiplier × BIK% × Personal tax rate
- Total annual tax = Annual car tax + Fuel benefit tax
It then converts annual cost to a monthly estimate so you can quickly compare vehicles and understand payslip impact.
Key terms to understand before you compare cars
1) P11D value
This is usually the list price including VAT and delivery, plus options, excluding first registration fee and road tax. It is not the discounted price your employer may have negotiated.
2) BIK rate
BIK rates are policy-driven and may change each tax year. Low-emission and electric vehicles generally have lower rates than high-emission petrol or diesel vehicles.
3) Personal tax band
If you are a higher-rate taxpayer, the same car can cost significantly more than for a basic-rate taxpayer. That is why two colleagues can pay very different amounts for the same vehicle benefit.
4) Fuel benefit
If your employer covers private fuel, tax can increase sharply. Many drivers are better off paying for private fuel themselves and claiming business mileage separately, depending on usage.
Example scenarios
Example A: Mid-range petrol car
- List price: £36,000
- BIK rate: 28%
- Tax rate: 20%
- Fuel benefit: No
Taxable benefit is £10,080 and annual tax is £2,016 (about £168/month).
Example B: Same car, higher-rate taxpayer with private fuel
- List price: £36,000
- BIK rate: 28%
- Tax rate: 40%
- Fuel benefit multiplier: £27,800
The annual tax can rise substantially once fuel benefit is added. This is where most underestimation happens in first-time calculations.
Ways to reduce company car tax legally
- Choose lower-emission vehicles: often the biggest lever for reducing BIK percentage.
- Consider electric vehicles: usually attractive for tax efficiency in many current regimes.
- Avoid private fuel coverage unless it truly saves money: fuel benefit tax can outweigh fuel received.
- Make employee contributions where allowed: this can reduce taxable benefit.
- Check model-year timing: tax bands can change, so delivery date can matter.
Common mistakes people make
- Using discounted fleet price instead of list/P11D value.
- Ignoring optional extras that increase taxable value.
- Forgetting to include fuel benefit.
- Applying the wrong personal tax rate.
- Using out-of-date BIK percentages from prior years.
Should you take a company car or car allowance?
This depends on your mileage, tax band, available models, and whether your employer covers maintenance/insurance. A high-BIK vehicle can make car allowance look better, while a low-BIK electric option can make a company car highly attractive.
Use this calculator as a first pass, then compare it against your employer's allowance package and estimated private ownership costs.
Final note
This tool gives an estimate for planning. For payroll-accurate figures, verify your exact BIK rate, tax code treatment, and applicable tax-year rules. If your situation includes salary sacrifice, mixed business/private use rules, or international tax residence, get professional advice.