Company car tax calculator
- Cash equivalent: the benefit in kind for the year
- £10,200
- Appropriate percentage applied
- 30
- Income tax the driver pays on it for the year
- £4,080
- That tax per month, through the tax code
- £340
Each figure on this page is HMRC's own method applied to the inputs you typed, with the rate and the page it was read from cited beside it and the date it was read. Carbikly publishes no dealer price, no lease quote and no advice on which car to take: the worked example is there to be overwritten with your own list price and band, and the rates are gov.uk's on the date cited.
The figures above start from a worked example (£10,200). Change the list price, the band or the rate and the sheet reworks as you type, the way it will when the new rates land each April.
Download the Company car tax calculator worked example (CSV)
Company car tax is worked from four things, and the monthly figure on the quote is not one of them. HMRC takes the P11D value, the list price when the car was first registered plus factory-fitted accessories, deducts any capital contribution the driver made up to the cap, multiplies by the appropriate percentage for the car's CO2 band and fuel type, reduces the result for any period of thirty days or more when the car was not available and for payments the driver makes for private use, and calls what is left the cash equivalent. The driver pays income tax on that figure at their marginal rate, through their tax code, and the employer pays Class 1A National Insurance on the same figure in July. This worksheet runs those steps on the car you enter, with the percentage table for the current tax year and the diesel supplement where it applies, and prints the tax per month the way it reaches the payslip.
What a fleet manager asks before trusting the Company car tax calculator
Is the P11D value what the company paid for the car? No. It is the manufacturer's list price when the car was first registered, including VAT, delivery and factory-fitted options, whatever discount was negotiated and whether the car was bought, leased or is second-hand. A cheaply leased car with a high list price is taxed on the high list price.
What if the driver only had the car for part of the year? HMRC reduces the cash equivalent for any period of thirty or more consecutive days when the car was not available, which the sheet approximates with months available. A car that arrives on 1 October is taxed on roughly half the year's figure.
Does Carbikly keep this for every car on the fleet? No: the sheet runs in your browser and nothing leaves it. Carbikly Pro keeps each car with its P11D value, band, fuel and dates, each driver with their rate, works this figure for every car each April, and reminds you before the P11D is due on 6 July.
Where the rates in this worksheet come from
Rates and thresholds for employers 2026 to 2027: the Class 1A rate on benefits.