To Grams
If you married prior to GC approval, your husband is qualified to apply follow-to-join visa. I don\'t think it related to tax filing.
If the spouse isn\'t in US, I don\'t think the person can file joint tax return because in the tax return form, if it is joint file, you need to fill in the SSN of the spouse, the person isn\'t in US can\'t have SSN.
That is what I think.