If you sold your primary personal residence and you lived in and owned the home for at least two years in the five year period on the date of sale, you do not have to report the sale if your gains are less then the exclusion amounts of $250,000 if filing Single or $500,000 if filing Married Filing Jointly (and both lived in the home for two years).
If you had a gain greater then the exclusion amounts then you would have to report the sale. Also, if you received a Form 1099-S for the sale either with a gain or a loss, the sale has to be reported.
Capital Gain or Loss = Sales Price (-) Sales Expenses (-) Adjusted Basis (Purchase price plus the cost of improvement prior to the sale)
See IRS Publication 523 Selling Your Home - https://www.irs.gov/pub/irs-pdf/p523.pdf
