Key word here is "may." They arise only if you deduct part of your mortgage principal payments in your HO deduction. In that case, the complication is that the amount you deducted over the years (not hard to figure out, involves adding up a few easily found numbers) must be subtracted from the purchase price of the home, giving an adjusted purchase price, before calculating the potentially taxable gain on the sale. That's it. If you don't deduct part of your principal payments, but deduct only part of your expenses like heating and repaving the driveway, this issue doesn't arise at all.