If you could have filed as no one's dependent for 2016 or 2017---you need to amend those years. For 2016 or 2017 if you were not someone else's dependent then you got a personal exemption of about $4000 that was income not subject to tax. That could have increased your tax refund. You have until midnight tonight to mail a 2016 amended return if you need to do ---after that it is too late to get a refund for an amended 2016 return.
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 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
**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.**
