@Pianofp --
Alabama will consider your father a resident for tax purposes if he is 1) domiciled in Alabama; or 2) if he maintains a "permanent place of abode" in Alabama. Per Alabama law, A permanent place of abode is interpreted to mean a dwelling place permanently maintained by the taxpayer; it is not necessary that he be the owner, or that he occupy it himself. Since your father still owns and maintains his Alabama home, it appears that his income remains taxable by Alabama - even though he is currently living with you in Tennessee.
Tennessee, of course, has no income tax.
Here is a link to the text of Alabama's law:
https://www.law.cornell.edu/regulations/alabama/Ala-Admin-Code-r-810-3-2-.01
**Answers are correct to the best of my ability but do not constitute tax or legal advice.
