where do i input a step up in basis from a real estate sale

[skideckel]

my mother sold her home for ~$500,000. my father and her bought the home 40 years ago for $10,000. my father died in 2017 when how was worth ~$250,000, where do i report the step up in basis when my father passed.

[MindyB]

You won't find a box specifically labeled "Step-up in Basis", instead, you'll enter the adjusted basis. To arrive at this number, you combine your mother’s original half of the purchase price ($5,000) with the fair market value of your father's half at the time of his death ($125,000), resulting in a total basis of $130,000. If they lived in a community property state, the basis "steps up" for the entire property, making her new basis the full $250,000 value from 2017.

In the TurboTax interview for the 1099-S, after you enter the $500,000 sales price and any selling expenses (like realtor commissions), you will reach a screen asking if you know the adjusted basis of your home.  Answer Yes, I will enter the amount. On the next screen there will be  box beneath the heading "Enter the adjusted cost basis of the home". Here, you should enter the calculated stepped-up amount ($130,000 or $250,000) directly into that field. 

Since the primary residence exclusion is handled automatically by the software, TurboTax will apply her $250,000 tax-free allowance against any remaining gain.

[NCperson]

@skideckel 

<<To arrive at this number, you combine your mother’s original half of the purchase price ($5,000) >>

Assuming not a community property state, your mother's half would also include half the cost of improvements from the date of original purchase through 2017 and ALL the cost of imrprovments from 2017 onward. 

if a community property state, your mother's half would include ALL the cost of improvements from 2017 forward and NONE of the improvement prior to 2017.