No, you cannot do that. Each tax year has to be prepared separately. You cannot fix last year's omission by putting it on your 2018 return. You can amend your 2017 return to include your mortgage interest paid in 2017.
https://ttlc.intuit.com/questions/1894381-how-to-amend-change-or-correct-a-return-you-already-filed?...
A 1040X cannot be e-filed. It must be printed and mailed. It will take about 3-4 months for the IRS to process an amended return. It is a good idea to use a mailing service that will track it, like UPS or certified mail, so you will know it was received.
Wait about 3 weeks from mailing and you can check the status of your amended return:
https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1
https://www.irs.gov/filing/individuals/amended-returns-form-1040-x/amended-return-frequently-asked-q...
https://ttlc.intuit.com/questions/1908543-do-i-need-to-amend
https://ttlc.intuit.com/questions/2566895-what-does-it-mean-to-amend-a-return
**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.**
