25C Residential Energy Credit Extended thru 12/31/13
Answer:
For purchases made in 2011, 2012, and 2013: Aggregate amount of credit is limited to $500. Taxpayer is ineligible for this tax credit if this credit has already been claimed by the taxpayer in an amount of $500 in any previous year.
For purchases made in 2009 or 2010: Aggregate amount of credit for all technologies placed in service in 2009 and 2010 combined is limited to $1,500