Company Car BIK Tax Calculator (UK)
Estimate your annual and monthly Benefit-in-Kind (BIK) tax for a company car. This is a planning tool, not tax advice.
What is BIK tax?
BIK (Benefit in Kind) tax is the tax you pay when your employer gives you a non-cash benefit, such as a company car that you can use privately. HMRC treats that private use as taxable income. The amount you pay depends on the car’s value, emissions, and your income tax band.
How this BIK tax calculator works
This calculator estimates your company car tax using the standard planning approach:
- Taxable car benefit = (P11D value − employee contribution) × BIK %
- Annual car tax = taxable car benefit × income tax rate
- Monthly car tax = annual car tax ÷ 12
- If private fuel is provided, an additional fuel benefit tax is added
For convenience, the calculator can estimate a BIK percentage from emissions, fuel type, and electric range. If you already know your exact BIK rate from HMRC tables, enter it in the override field for a more precise result.
Inputs explained
P11D value
This is usually the list price of the car plus optional extras and delivery, before first registration fee and road tax. Your payroll or fleet team can provide this figure.
CO₂ and fuel type
Lower-emission cars generally get lower BIK rates. Fully electric vehicles usually receive the lowest rates, while higher-emission petrol/diesel cars attract higher percentages.
Electric-only range
For plug-in hybrids and low-CO₂ cars, electric range can materially affect the BIK percentage, so entering this helps refine the estimate.
Employee contribution
If you personally contribute toward private use, this can reduce taxable benefit (subject to HMRC rules). Keep records in case your employer or accountant needs to verify them.
Worked example
Suppose you have:
- P11D value: £40,000
- Estimated BIK rate: 12%
- Tax band: 40%
- No employee contribution
Your estimated taxable benefit is £4,800 (£40,000 × 12%). At 40% tax, estimated annual BIK tax is £1,920, or about £160 per month.
Tips to reduce company car tax
- Choose lower-emission or fully electric vehicles where practical.
- Confirm the exact BIK band before ordering a vehicle.
- Check whether a cash allowance could be more efficient for your case.
- Avoid employer-paid private fuel unless your private mileage is very high.
- Review total cost of ownership (insurance, charging/fuel, maintenance), not tax alone.
Frequently asked questions
Is this calculator official?
No. It is an estimate tool for planning. Always verify with current HMRC guidance, your payroll team, or a qualified tax adviser.
Does diesel always have a surcharge?
Some diesel vehicles may be affected by a supplement depending on emissions standards and HMRC rules. This calculator applies a simple planning surcharge model.
Can BIK rates change each tax year?
Yes. Rates and multipliers can change over time. Recheck your numbers whenever tax policy updates.
Final note
Use this BIK tax calculator as a fast way to compare options and avoid surprises in your monthly payslip. For final decisions, confirm values directly from your employer’s fleet data and HMRC documentation.