My mom passed away in 2020. Three brother inherited the home in 2021. Three brothers sold the home in 2024. How do I report this sale on tax return.

Often the best way to get a fair market value on a real estate property is to enlist the help of a real estate professional. Perhaps the agent/office that handled the sale will be able to help.  They should be able to look up the past values of area comparable homes to get you a fair market value on the home the heirs sold.  

Finding the historical fair market value of a property can be challenging but you will need that to take advantage of the stepped up basis on the inherited property to reduce the taxable gains on the sale. 

Once you have that figure the heirs each will enter their part of the fair market value as the cost basis and their part of the sales price as the proceeds for the transaction for their tax returns.  There will also be an opportunity to enter their portions of selling costs to offset some gain as well (see link below).  

In TurboTax navigate to the "Investments" topic in the "Wages and Income" section.  Select "Add an Investment" and the "Other (land, 2nd home...) tile and enter the requested information.

Typically, the an inherited home sold soon after inheritance has little if any taxable gain. 

IRS Publication 523 has more detailed information on selling a home.  Refer to the section on basis adjustments for selling costs that can be used for example.