Principal residence refers to a dwelling where the borrower maintains or will maintain their permanent place of abode and typically spends or will live in the house the majority of the calendar year. A person may have only one principal residence at any one time. At least one borrower must occupy the property within 60 days of signing the security instrument and intend to continue occupancy for at least one year. A person in military service must meet the requirements of 24 CFR 203.31.
For additional information see Handbook 4000.1 II.A.1.b.iii.(A)(1)-(2) available at http://portal.hud.gov/hudportal/HUD?src=/program_offices/administration/hudclips/handbooks/hsgh