Tax on Company Cars?

How much tax are you charged for the use of company cars. Is it charged annually or based on mileage or combination....??

why would you pay tax for a co. car? unless you the owner, in tat case you pay annually. What you might pay more according to the expected mileage for the year is insurance.

If you mean taxed on your wages as opposed to paying the road tax, not sure how much it is but quite a lot and it's taken monthly from your wages and has nothing to do with how much you use the car. Even though you have to pay a lot more tax, remember the company pay for the insurance and all the maintenance of the car so you'll just have to work out which is more beneficial for you personally.
Look at the Inland Revenue website if based in the UK as they have all details.
If you have a company car you are charged a car benefit which is calculated by reference to the new list price of the vehicle (regardless of its age) and if the company also supplies a fuel card (or reimburse you for the fuel) then you are charged a benefit on that also because you will have the opportunity to use if for private use also.

Go to http://cccfcalculator.inlandrevenue.gov.... for a calculator. It might be worth opting out by receiving a lump sum payment instead.
Tax Specialist.
Just to add one point to the excellent answer by NotMarriedNoChildren the percentage of the list price on which you are taxed depends on the carbon dioxide emissions of the car you have been provided with.

You can check this figure at www.smmt.co.uk