 The qualified plug-in electric vehicle credit phases out for a plug-in manufacturer over the one-year period beginning with the second calendar quarter after the calendar quarter in which at least 200,000 qualifying plug-in vehicles from that manufacturer have been sold for use in the U.S.Cumulative sales started counting sales after December 31, 2009.After reaching the cap, qualifying PEVs for one quarter still earn the full credit, the second quarter after that quarter plug-in vehicles are eligible for 50% of the credit for six months, then 25% of the credit for another six months and finally the credit is phased out.