Question: I understand IRS data will show up as the individual applies for exchange, but isn’t subsidy based on household income and if so how will that coordinate?
Answer: If more than one tax return is filed within a household, you would probably have some options. Let’s say the household consists of a husband, wife, and 24 year-old daughter. The parents filed jointly. but the daughter filed a separate return. I would think you could either combine both incomes and test the subsidy-eligibility for that household as a family of three. The second option would be to for the parents to qualify separately from the daughter based on their separate incomes. Note that this answer is an educated guess. I have not seen any specific rule treating this situation.