On your filed return, did you claim the standard deduction or did you itemize? If you took the standard deduction and this 1098 was for a relatively small amount, you might not have to do anything.
However, if you did itemize or if this impacts your state return, you will want to amend your return. There should be an amount in Box 2. If it is blank and your mortgage company is not going to issue a corrected Form, you will need to get the outstanding principal on the date the mortgage originated and use this as your Box 2 amount.
If you do need to amend the federal return, I would file the original state return and amend that one as well if it impacts your state return. I also would hold off on filing your amended returns until your original return is processed and you have received your refund if you are getting one. Don't worry, you have up to 3 years to amend a return from its original due date so there's no hurry.
