I have received more information concerning my taxes. (Got lost in the mail). I have already submitted my return. How difficult would it be to file an amended?

[Carl]

Has your return been received by the IRS and processed? I ask since you state it was lost in the mail. If not received by the IRS, then you don't have a processed return to amend. In such a case (lost in the mail) you've not even submitted an original return yet.

[connielee64]

No, the return was efiled (submitted). I received a late 1098 that I didn't have when preparing the return.

[Texas Roger · Accepted solution]

If your efiled return was accepted, then you need to amend your return to enter the 1098.

If your return is rejected by the IRS, you can correct the problem and fix the reason for rejection and re-efile your return. If your return is accepted by the IRS, you must prepare, print, sign and mail an amended tax return form 1040X to correct the problem. 

DO NOT change your original tax return until you start the amended return. If you have already changed it from the way it was originally filed and accepted, you must change it back before you start the amended return. Wait until you receive the refund from your original return before beginning your amended return to make sure you enter the correct amount. An amended return cannot be efiled. Here is an FAQ to help you:                                                                  

https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed