Do I claim rent if I pay for my partners mortgage ?

[xmasbaby0]

No.    It sounds like you have a cost-sharing arrangement with someone else whose home you live in.  Family cost sharing is not entered on a tax return.  If you are not on the deed or the mortgage, you cannot enter anything about the mortgage interest on your tax return.   And rent is not deductible on a federal tax return.

[Hal_Al]

If you are asking about a state rent credit, identify the state. But, the answer is probably no.