The Revenue approved figure for mileage allowance which can be paid tax free was raised from 6 April 2011 to 45p for the first 10,000 miles, but stays at 25p thereafter (despite the increase in the cost of petrol).  If you receive a lower rate from your employer than 45p per mile, you can claim the difference against your personal tax liability provided you retain the appropriate records.  Please let us know if such a claim should be included on your tax return.