"I did my return online...."
If you used the 2019 online software and entered 2015 income information into it and then mailed it, what you did was file a VERY incorrect 2019 tax return. The IRS might catch the mis-match between the income you reportted and send you a letter. If they actually process it and send you a tax refund--you are not entitled to that refund and must send it back. It is too late to receive a tax refund for any tax year earlier than 2017.
If you just mailed it in November it will take quite awhile before you hear anything. It is taking a very long time for the IRS to process mailed returns.
**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.**
