First, what is your capital gain.
Your gain is the difference between the selling price and the adjusted cost basis. You can reduce the selling price by the transactional costs of selling (real estate commission, transfer taxes, inspections you pay). Your adjusted cost basis is the price you paid for the home, plus any permanent improvements, minus any depreciation you took or could have taken for business use of the home. (Repairs are not improvements.)
Then, if you lived in the home as your main home for at least 2 years of the past 5 years, you can exclude the first $250,000 of gain (or $500,000 if married filing jointly). If you have more gain than that, it will be taxed at 15% or 20% depending on your other income. (Plus state income tax.)
If your gain is less than your exclusion, and if you did not get a 1099-S form at the closing, you don't even have to report it on your return. If you did get a form 1099-S (no matter what your gain is) or if your gain is more than the exclusion amount, you must report it.
