|HMRC now reviews the advisory fuel rates quarterly. The rates effective from 1 March 2012 can be found at http://www.hmrc.gov.uk/cars/advisory_fuel_current.htm and a summary of the VAT figures, along with historical rates, can be found in the attached document.
For one month from the date of change, employers may use either the previous or new current rates, as they choose. Employers may therefore make or require supplementary payments if they so wish, but are under no obligation to do either.
The advisory fuel rates are provided by HMRC as guideline fuel only mileage rates for company cars. They can be used to negotiate dispensations for mileage payments for business travel in company cars and are intended to reflect actual average fuel costs.