Calculate your estimated company car BIK tax
Estimate only. Tax rules can change and personal circumstances matter.
If you have a company car in the UK, Benefit in Kind (BIK) tax can make a big difference to your take-home pay. This quick BIK car tax calculator helps you estimate your annual, monthly, and weekly tax cost from your vehicle benefit.
What is BIK car tax?
BIK car tax is the income tax you pay when your employer provides a car for private use. HMRC treats that perk as a taxable benefit. The amount of tax you pay depends mainly on:
- The car’s P11D value (roughly list price plus options),
- The car’s BIK percentage (set by emissions/fuel type and tax year),
- Your income tax band (20%, 40%, or 45%),
- Whether private fuel is provided.
How this BIK calculator works
This page uses a straightforward estimate based on standard BIK logic:
- Car taxable benefit = P11D value × BIK %
- Fuel taxable benefit (if included) = Fuel benefit charge × BIK %
- Total taxable benefit = Car benefit + Fuel benefit − Employee contribution
- Estimated tax due = Total taxable benefit × Income tax band
It then converts annual tax into monthly and weekly estimates so you can budget more easily.
Worked example
Example scenario
Suppose your details are:
- P11D value: £40,000
- BIK rate: 25%
- Tax band: 40%
- Employee contribution: £1,000/year
- No private fuel benefit
Your estimated taxable benefit would be £10,000 minus £1,000 = £9,000. Tax at 40% gives an annual BIK tax estimate of £3,600, or about £300 per month.
How to use this calculator accurately
1) Confirm your correct P11D value
Use your official company car documentation or payroll details. Guessing this number can distort your estimate.
2) Use the right BIK percentage for your tax year
BIK percentages are year-specific and vary by CO₂ emissions and fuel type. Electric cars usually have lower BIK rates than high-emission petrol or diesel cars.
3) Include private fuel only when relevant
If your employer pays for private fuel and you do not fully reimburse it, this can significantly increase your tax bill.
4) Check your income tax band
A higher tax band dramatically increases the same BIK benefit’s tax cost. Two employees with the same car can pay very different BIK tax.
Ways to reduce your BIK tax
- Choose a lower-emission vehicle: Lower emissions often mean a lower BIK percentage.
- Consider electric vehicles: EVs often receive favorable BIK treatment.
- Avoid private fuel benefit if costly: In many cases, paying for private fuel yourself can be cheaper.
- Review salary sacrifice options: Depending on scheme design, this can improve overall tax efficiency.
- Review total reward package: Compare car benefit vs. car allowance on a net-pay basis.
BIK car tax vs car allowance
A company car can still be good value, especially if insurance, maintenance, and servicing are included. But in other cases, a cash allowance may provide better flexibility and lower tax burden. The best option depends on annual mileage, vehicle type, employer scheme terms, and your tax band.
Frequently asked questions
Is this calculator official HMRC advice?
No. It is an estimate tool to help planning. Always verify with current HMRC guidance or a qualified tax adviser.
Does this include National Insurance?
No. This calculator focuses on employee income tax impact for BIK. Employer Class 1A NIC and payroll specifics are separate.
Can employee contributions reduce BIK?
They can, depending on the type of contribution and scheme setup. This calculator applies a simplified reduction for planning purposes.
Do BIK rates change every year?
Yes. Check the correct rate for your exact tax year, fuel type, and emissions profile.
Final note
Use this BIK car tax calculator as a practical first pass before choosing your next company car. A quick estimate now can prevent a surprise reduction in monthly take-home pay later.