Haven't done it myself, but I had some friends go through a ridiculous amount of hassle getting an ACA plan for their family (with a baby daughter). They had to go back and forth dozens of times to try and prove their income to get the premiums set up with the right subsidies. They were repeatedly denied because the bureaucrat looking at their application didn't think they provided enough documentation of their income or something. Then they would submit more documentation and the next bureaucrat would find a different thing wrong with it. It was complicated by the fact that they had moved recently and didn't have steady employment yet (hence why they needed a subsidized plan in the first place). My guess is they would have had little problem if they had been able to pay the full premium up front and let the subsidy sort itself out at tax time.