Firstly, if anything is taxable, it's not the amount of profit or sales proceeds.
Capital gains is the difference between the selling price and the cost basis. Suppose the home was bought for $100,000 and sold for $500,000, but there was only $50,000 of cash because there was a $450,000 mortgage. The capital gains is still $400,000.
Second, it matters if you were a co-owner. If you owned the home, and lived in it as your main home for at least two years, you can exclude up to $250,000 of capital gains. You might have been a 1/3 owner, or a 1/2 owner, or something else, we don't know. Or maybe you were not an owner but your father was.
Third, if you were not an owner, then the owner who sold the home is responsible for all the taxes, and any money you got was a non-taxable gift.
Did you have to sign papers to sell the home? Did your father have to sign papers?
