I respectfully disagree with your statement that "Texas law does not apply to your federal tax return."
With respect to you marital status, I believe that state law does apply. Marriage is a state regulated status, not a federally regulated status.
In Texas, (and at least some other states), you are either married, or you are not.
The questioner notes that he is still married.
Further, Quoting from https://www.divorcenet.com/resources/legal-separation-in-texas-faqs.html
"Legal Separation isn't available in Texas, so couples who would like to end their marriage formally must follow the state's divorce process. However, the court allows couples to live apart and make temporary arrangements while a divorce is pending."
Even more important is the IRS definition of marriage: "In general. Except as provided in paragraph (b)(2) of this section regarding marriages entered into under the laws of a foreign jurisdiction, a marriage of two individuals is recognized for federal tax purposes if the marriage is recognized by the state, possession, or territory of the United States in which the marriage is entered into, regardless of domicile. "
https://www.law.cornell.edu/cfr/text/26/301.7701-18
Thus, the questioner is still married, and hence not able to file as head of household.
Agree? Disagree? I am open to comments.
