Any claim for the Alternative Fuel Tax Credit for a alternative fuel vehicle purchased in 2011 will prescribe after December 31, 2015. The prescriptive period for filing a refund claim (e.g., an amended return claiming the credit) is three years from December 31st of the year the taxes were due, or one year from payment, whichever is later. Therefore, it is still possible to amend 2011 and later year returns. 2011 will prescribe after Dec. 31, 2015 (2011 income taxes are due in 2012, three years from Dec. 31 of 2012 is Dec. 31 of 2015). See Instructions for 2011.