you must have own and lived in the house as your principal residence for two years (730 days - temporary absences are ignored) out of 5 years ending on the date before the date of sale. so you have until 7/30/2021 to sell to get the principal home sale exemption (7/31/2016-7/30/2018 would be the two years). however, if you have a profit, to the extent that it is less than or equal to the depreciation allowed or allowable you will pay taxes on the depreciation recapture (not more than the gain).
you don't say whether you are married but if you are your and your spouse occupied the house for 2 out of the 5 years then filing a joint return the exclusion is $500,000. if single the exclusion is $250,000
as an FYI do not wait until the last minute to sell. if the closing is delayed or you can't find a buyer you could lose the exemption which would be costly
the only way to avoid depreciation recapture if there is a gain and capital gains tax if the gain exceeds the exclusion is to do a 1031 exchange - you exchange your rental property for other rental real estate. any cash you get out of the deal would be taxable. you'll need a lawyer to make sure it is handled properly and find an exchange agent to hold the sales proceeds. the one person I know who tried doing it on his own messed up resulting in the gain not qualifying for deferral - he thought he could hold the cash from the sale until he bought a replacement property - not allowed.
