Deductions & credits

Yes, you can file an amended return and file as HOH if your Dad is a Qualifying Relative in 2023.

Qualifying relative

A qualifying relative must meet general rules for dependents and pass these tests:

• Not a qualifying child: Isn't your qualifying child or the qualifying child of any other taxpayer
• Member of household or relationship: Lives with you all year as a member of your household or is a specific type of relative
• Gross income: Has gross income under $5,050
• Support: Gets more than half their financial support from you

See the full rules for a qualifying relative

You seem to be very well-informed!