the only way to know for sure is to prepare MFS for each of you and then a joint return. desktop software would be best since you only pay for the app. note that for purposes of deducting mortgage interest on MFS returns you can only claim it on one residence, not 2 as with a joint return also the mortgage debt limit is cut in 1/2. I have tried the tax calculator and it's not as sophisticated as the full program so results would likely vary.
