To get to the correct place in TurboTax, type in Form 3468 in the search box and that will take you to the investment credit section where you claim the rehab credit. Follow the prompts for entry.
The rehab credit is claimed in Part 3, Page 2 of the form.
I am not sure what state you are in, but you will access in the state interview and it should be in a section titled "credits" or "credits/deductions" specific to your state. If you do not see it in the interview, switch to forms mode to see if you need to do direct entry on the form.
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What is Form 3468: Investment Credit - TurboTax Tax Tips ...