I don't know how much help my experiences will be to you, but here goes.
In 2014 DH left his job, and thus our insurance thru his employer. He expected to get a new job quickly, but a hiring freeze slowed things down. We applied thru our state website (NY), and were told we have to go on Medicaid, with the kids on CHIPS. I learned that while the federal side uses AGI, the state looks at monthly income. Since at that moment DH was earning zero, and I work part-time, we were eligible for Medicaid per the state, despite knowing that our annual AGI would be higher.
Things were always massively messed up. They insisted DS4 was in their system already (incorrect) and that held things up. They issued cards for 2 of the 3 kids at home, none for the rest of us. I never figured out how to add our college age son (gray area - not our tax dependent, so can't add thru marketplace, but by ACA eligible to be on our plan if under 25 years old). When we finally got employer coverage, I tried to notify the state thru the website, as directed, but it locked up on the info. I called them for assistance, and everything the assistant told me to do refused to cooperate on my side. She eventually reset data from her side and said we were good. I asked about the tax forms, and was told they'd automatically be sent. We never received anything. DS2 had a small fine for the few months he had no coverage. We are all just lucky we didn't need to make any medical claims during that period.
The important things that learned were: the differences in viewpoint (monthly vs annual income), you must apply at least a month in advance (if you are approved before the 15th of the month, coverage may begin the 1st of the next month; if later, then coverage begins a month later; the quality of phone assistance varies greatly, so keep trying until you get a great one. Oh, and the NY website is, or at least was, so problematic as to be unusable. If I ever have to do it again, I will go thru a Navigator.
