Where to enter stolen property loss?

The new tax law eliminated the deduction for theft losses for 2018 through 2025, so you don't enter it anywhere.

Your state might still allow a deduction for a theft loss. Check the income tax instructions for your state, or your state's income tax web site. If your state allows the deduction, depending on the state there might be a place to enter it in the state interview, or you might have to enter it in the federal interview. To enter it in the federal interview, enter "theft" (without the quotes) in the Search box, then click the link that says "Jump to theft."