Coleen, thank you so much for the detailed and thoughtful response here! This exactly the kind of information I was trying to research. Based on what you said, I think we should be in the clear, and it'll be a matter of having this accurately reflected on our amended return. You wrote, "If this information changed during 2017 and you did not promptly report it to the Marketplace, the amount of APTC paid may be substantially different from the amount of PTC you can take on your tax return." That's just it: we DID promptly report it to the HealthCare.gov folks. We explained to them in September that we were ending our coverage because my wife got a new job that was paying substantially more and included employer-provided insurance. That's reflected in the 1095a, with the September column being a much smaller, pro-rated dollar amount, and October-December being "0." I have a separate 1095c form for the new insurance that began with the new job in September, but TurboTax says that it doesn't want/need the information from this document.
