Not sure if it matters, but we do not live in a community property state, have no dependents and we both itemize. This is not ideal for his taxes, but the benefit to me (I own our house and take those deductions) generally outweighs the impact to him.
The wording on the healthcare portion of the tax form is confusing because it talks about "household" with out any mention of who is considered part of your "household" when you are filing separately from your spouse. Am I my own "household" or do I still list his information even though he's filing separately?
I tried adding in his ACA info, but that resulted in us BOTH repaying his ACA subsidy (me: in-full + him: partial = repaying more than he took as subsidy). But if I don't list it on mine then that leaves him only repaying part of it when I don't believe we qualify for assistance.
Something you are doing is not correct. If you each file separately, he is not eligible for any premium tax credit, and would have to repay all of it. Household size should be moot, and you should leave any mention of his policy off your separate return.