If your name is on the loan and you are legally obligated to make the payment then, yes, you can claim any interest that you paid.
The farthest back that you can amend for a refund is 2016 and the 3 year limitation on 2016 runs out April 15, 2020.
Amended returns can only be mailed. It is suggested that it be mailed certified with return receipt (or other tracking service) to verify that the IRS receives it.
See this TurboTax FAQ for detailed amend instructions:
https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed
You can check the status of the amended return here, but allow 3 weeks after mailing.
https://www.irs.gov/filing/wheres-my-amended-return
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
