It would not be possible to designate it your primary residence unless you or your spouse uses it primarily for household purposes (ie >50%). There are some exceptions for tempory absenses, but none would apply in the case where you bought the house and moved in later. Should you really move in later, you will be allowed a primary residence exclusion upon later sale, but the capital gain that qualifies for this exclusion will be time-apportioned and only the part of the profit that relates to the time you acutually used the house as a primary residence can be reduced by the primary residence exclusion. The rest of the capital gain will be fully taxable (although there is always the annual exclusion that is R15000 for the 2008 tax year).