No you cannot use the interest you paid on your student loan in 2015 on your 2016 tax return. You can amend your 2015 tax return to include it for 2015. You can use the interest you paid in 2016 on your 2016 return.
https://ttlc.intuit.com/questions/2952222-how-do-i-amend-the-2015-taxes-i-filed-with-turbotax-online
Only the person whose name is on the student loan and who is legally obligated to pay the loan can deduct the student loan interest. If you did not sign or co-sign for the loan you cannot deduct the interest.
You cannot deduct student loan interest if you are being claimed as someone else’s dependent, or if you are filing as married filing separately.
The student loan interest deduction can reduce your taxable income by up to $2500
Enter the interest you paid for your student loan by going to Federal>Deductions and Credits>Education>Student Loan Interest Paid in 2016 (Form 1098E)
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
