Sorry for your loss. You cannot file a 2019 tax return yet. The software to file a 2019 tax return will not be released until late November 2019, and the IRS will not be accepting 2019 tax returns until late in January of 2020.
Or are you really asking about filing a 2018 tax return for her--that would be filed in 2019? Are you the executor of the estate?
**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.**
