You will get any subsidy owed to you during your tax returns if you didn't already collect it. If you know your income will be lower you can write a letter stat

You will get any subsidy owed to you during your tax returns if you didn't already collect it. If you know your income will be lower you can write a letter stating your expected income and get the subsidy applied every month (at least in my state). In this case, during tax returns, you'd have to pay back any subsidy amount which you didn't deserve.