Medicare definitely counts as qualified coverage. Large-company provided insurance should too. With smaller companies, who knows? My hunch is their insurance providers wrote them new plans if the old ones weren't qualified. It won't matter for filing season 2015 (tax year 2014) because the employers and insurance companies were given an extension to report these things until 2015, and the IRS has no way of checking (their admission) if 2014 plans were qualified.
People who got insurance through the exchanges or don't have insurance will be the complex ones. The exchanges will provide a form showing how much advance premium credit they got, it any. I went to a seminar this week and everyone breathed a collective sigh of relief when the speaker said all you need to know is household size, household income, and the numbers on the exchange form. The software does it all! (He uses Ultratax, not sure about ATX.) Household income can be tricky though. For example, nontaxable Social Security income counts for all household members, including kids who might be getting SS from a deceased parent's account. Hopefully this was all included in the exchange enrollment questions, so there should be no surprises. For those with no insurance, the software will do it all. Unless of course the taxpayer qualified for an exception. Best to read up on those.
That said, we still have to be able to explain it to the client, and that will take education. (Kind of like explaining why part of a client's SS is taxed--you can't unless you understand the math.) And there will be kinks galore. I just researched what happens if someone who gets an advance credit gets married. One would think income for the unmarried months would be used to calculate the credit. Nope. Total household income on the joint return is divided in half, as if each spouse earned half the income during the year. The credit is calculated on that amount. So if a guy who earned $25k and got a premium credit marries in December to someone who earned $75k, he would be treated as if he had earned $50k and have to pay the whole advance back.
These unusual situations should be rare, but if we typically help our clients with tax planning we really need to get educated.