Can I claim mortgage interest deduction if my name is not on the mortgage or deed but I paid all the payments and live at the house with my brother. We are 50/50 owners

Yes. The rules to claim mortgage interest state: "The mortgage is a secured debt on a qualified home in which you have an ownership interest. Secured Debt and Qualified Home are explained later." from Publication 936 (2023), Home Mortgage Interest Deduction.

Secured debt means the house is used against the mortgage, if you don't pay the mortgage, they get your house. You own the house. A qualified home is your main home or second home. Your home is at stake if you don't pay the mortgage. You get to claim all related expenses as the owner.

@Ms Tee

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