What happens when you switch from Obamacare to Medicare? Today 9:30 PM Q. What happens when you switch from Obamacare to Medicare? Can someone continue to get an Affordable Care Act premium tax credit until Medicare coverage starts? IRS 2019 Publication 974 states in an example that you can. In other words, if your birth month is September and you sign up for Medicare in November, your Medicare coverage starts Feb. 1. You should be able to continue to get your premium tax credit Feb. 1, even though you turned 65 earlier in September, right?— Confused A. It’s a great question. You cited a 2019 IRA publication.