Yes, for 2020 you may still file MFJ and include both of your tax related information. For 2021, you would file Single. Please be aware of potentially being in a different (higher) tax bracket for 2021 when filing Single. The tax brackets and deductions for 2021 are online, please research and plan accordingly.
Yes, you will still file married filing jointly. The final return is filed on the same form that would have been used if the taxpayer were still alive. You would enter all of his information. For more information on this subject, see the following Help Article: Death in the Family
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Yes - For 2020 you will file a joint return with your husband, including his income as well as yours. Starting in 2021, you will use the filing status of Single or Qualifying Widow. To be considered a qualifying widow/widower you must have a dependent child .
For more information please see the following: