If your father owned and lived in his home for two of the five years before the sale,
then up to $250,000 of capital gain is tax-free. If he is married and file a
joint return, the tax-free amount doubles to $500,000. The law lets him
"exclude" this otherwise taxable profit from his taxable income.
Please read this TurboTax article for more information:
https://turbotax.intuit.com/tax-tips/home-ownership/tax-aspects-of-home-ownership-selling-a-home/L6t...