Oh yeah, if your income goes up, your subsidy would obviously go down, and vice versa. You are supposed to make adjustments as they happen.
For example, if you applied for insurance with a $30K a year income, and 4 months into the year you got promoted to a $35K a year position, you are supposed to go to your account and update your income level.
You might also get demoted and need to adjust your income for a bigger subsidy.
If your income goes down, you would get money back.
This explains the APTC and income changes and taxes pretty well.
However, It would still really all end up basically the same, I think.
You would either have paid the extra money at the end of the year, or paid the extra money monthly as a higher premium.
Either way, you pay. They get you coming and going.................