company car tax benefit calculator

How company car tax works

If your employer gives you a car for personal use, HMRC typically treats that as a taxable benefit. This is often called a Benefit in Kind (BIK). The amount you pay depends on your car, your tax band, and the official BIK percentage for that vehicle.

In simple terms, the taxable car benefit is:

• P11D value of the car
• multiplied by the BIK rate (based mainly on CO₂ emissions and fuel type)
• minus any eligible employee contributions.

If your employer also pays for private fuel, there is usually an additional fuel benefit charge that can significantly increase your tax bill.

What this calculator includes

• Estimated BIK percentage from tax year, fuel type, CO₂, and electric range
• Taxable car benefit amount
• Optional private fuel benefit estimate
• Your estimated annual and monthly personal tax cost
• Estimated employer Class 1A National Insurance contribution

Key inputs explained

P11D value

This is usually the list price of the car plus accessories and delivery charges (before first registration fee and annual road tax). It is not the same as what your employer paid after discounts.

CO₂ and electric range

Lower CO₂ generally means a lower BIK rate. Plug-in hybrids with longer electric-only range can also receive lower rates than similar models with short range.

Income tax band

Your personal tax rate matters: the same taxable benefit costs twice as much tax for a 40% taxpayer compared with a 20% taxpayer.

Private fuel benefit

Many people underestimate this. If private fuel is provided, tax is calculated from a fixed multiplier and your BIK rate. For many drivers, paying for private fuel personally can be cheaper than accepting the fuel benefit.

Quick example

Suppose you have a car with a £42,000 P11D value, a 13% BIK rate, and you are in the 40% tax band:

• Taxable car benefit = £42,000 × 13% = £5,460
• Annual tax = £5,460 × 40% = £2,184
• Monthly tax impact ≈ £182

If private fuel is included, your total taxable benefit can climb quickly, so always compare both scenarios.

Ways to reduce company car tax

• Choose lower-emission vehicles where practical
• Consider fully electric models if charging and mileage patterns fit
• Check whether an equivalent cash allowance is more efficient for you
• Track employee contributions accurately
• Review whether private fuel benefit is truly worthwhile

Company car vs car allowance: what to compare

A company car can be attractive because costs like maintenance, insurance, and breakdown cover may be bundled by your employer. But a cash allowance gives flexibility. Compare:

• Net take-home pay after tax
• Fuel and charging costs
• Insurance and servicing responsibility
• Mileage reimbursement policy
• Contract length and early-exit penalties

Important note

This page uses a simplified model designed for quick planning. Real payroll outcomes can differ due to precise HMRC banding rules, pay period treatment, approved emissions status, and employer policy details. Use this as a decision aid, then confirm numbers with payroll, HR, or a qualified tax advisor.