A principal residence is the home where you live most of the time. The home must be in the United States. It can include a house, houseboat, mobile home, cooperative apartment, condominium, and a manufactured home.
Per the IRS: “THE PRINCIPAL RESIDENCE OF A TAXPAYER IS DETERMINED BY TAKING INTO ACCOUNT ALL THE FACTS AND CIRCUMSTANCES, SUCH AS THEIR PLACE OF EMPLOYMENT AND MAILING ADDRESS FOR BILLS AND CORRESPONDENCE, BUT ORDINARILY WILL BE THE PROPERTY WHERE THE TAXPAYER SPENDS THE MAJORITY OF THEIR TIME. TREAS. REG. § 1.121-1(B).”
Details for Claiming the Energy Efficiency Home Improvement Credit:
- Taxpayers claiming the credit for exterior doors, windows and skylights, insulation materials or systems, and air sealing materials or systems: the home must be located in the United States and must be owned and used by the taxpayer as the taxpayer's principal residence (does not include renters, nor does it include second homes);
- Taxpayers claiming the credit for central air conditioners; natural gas, propane, or oil water heaters; natural gas, propane or oil furnaces or hot water boilers; electric or natural gas heat pumps; electric or natural gas heat pump water heaters; biomass stoves or biomass boilers; and improvements to panelboards, sub-panelboards, branch circuits, or feeders: the home must be located in the United States and used as a residence, including a second home, by the taxpayer (includes renters who make eligible improvements); and
- Taxpayers claiming the credit for a home energy audit: the home must be located in the United States and owned or used by the taxpayer as the taxpayer's principal residence (does not include second home) and (includes renters who make eligible improvements).