You need to arrive at the value of the home as of the date of her passing; that is your cost basis. Then any gains from sale above that would be subject to capital gains. You may look to discuss this situation with the CPA or tax attorney that is working on your mother’s estate tax return.
Adam C. Harding, CFP
Disclosure: For informational purposes only. Not to be considered investment, tax, or legal advice. My responses on Nerdwallet are for educational purposes only and action should not be taken until a thorough analysis has been done by me or your financial advisor. Investing involves risk of loss and diversification does not ensure protection against risk of loss.