It is a bit (way!) more complicated that.
You must start with your spouses original tax return as filed, and *amend* that to joint and then add *your* information to that amended return.
You cannot just file a *new* 2018 tax return as joint.
The same for 2019.
You might want to see a tax professional since there might be a lot of back tax that a professional can possibly mitigate.
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**
