I co-signed a mortgage with my husband in 2018 before we were married in 2020. Is my portion of the outstanding mortgage principal 100% or 50% of the outstanding balance?

[hbphil]

I claimed 50% of the interest paid deduction.

[JotikaT2]

It depends.

You and he will need to discuss to determine what percentage of the loan belongs to each of you.  

[hbphil]

Thank you @JotikaT2 . I filed my returns with this amount listed as 100% - but a 50% split reflects how we manage the mortgage. Will this affect the outcome of filing in such a way that I need to submit an amendment? 

This is good feedback for Turbo Tax and something to be clarified on the online form. This section of the online form has two prompts: one for "your portion" of the outstanding mortgage balance, and then lower on the page, simply "outstanding mortgage balance." If you put the full amount in "outstanding mortgage balance," it overwrites the "your portion" box above.