factors to consider:
your place of employment or distance to it old vs nrew
where family members live - that includes you and since you are renting A, I would say B
address currently used for such things as tax returns, driver's license, voting, bills and correspondence, auto registration - this would probably be B
nearest to your banks (?)
is the move to B permanent for the foreseeable future (ie as of now no intent to return to A)
the actual tern used is principal not primary
since A was rented more than 14 days, the rent is reportable on schedule E. expenses must be prorated
depreciation must be taken ( use the lower of your cost or FMV when you started to rent it).
