How do I calculate my BIK tax?

To calculate your BIK tax, you multiply your BIK band percentage by your car’s P11D. The BIK percentage banding is worked out by the amount of CO2 that your car emits, as indicated by the g/km rate. These percentages change every tax year, a list of BIK tax bands can easily be obtained. The final BIK tax is then adjusted to suit your annual salary, but only slightly. To do this you multiply your figure by your tax rate, 20, 40 or 45.