I haven't filed for the last couple of years. Now, I need to file for 2015, 2016 and 2017 returns. I need to do the federal and california state. Can I use these desktop versions to e-file prior year returns?
Prior year tax returns cannot be e-filed. You have to print, sign, and mail them. Do not combine any different tax years in the same envelope when you mail them. Mail them separately.
When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS received the return.