Using just released TT 2018, I entered my expected income data and expected date for ACA for 1095-A. This data supports a premium tax credit of $1,900/month and I get an expected refund of premiums paid by me in excess of the advance credit.
Here's the fun part. I go back and increase my income by increasing a 401K distribution such that AGI is now well beyond the income threshold for my family premium tax credit eligibility. So the $1,900/month credit I received all year long is no longer valid and I should have to pay that money back in this case. Increasing my income did nothing to this, still said I was due a refund of excess paid in. This isn't right, correct?
I was doing this to make sure I would not exceed the income threshold if I needed to take an unplanned 401K distribution in December.
The Form 8962, Premium Tax Credit has not yet been finalized so that is why you are not seeing the change when adding income on your tax return. The TurboTax program will have several updates before it can be used to file a 2018 tax return.
You can see which forms and schedules have not been finalized for your tax return in the Federal Review section of the desktop program.
Also, use this TurboTax support FAQ for the federal forms availability - https://ttlc.intuit.com/questions/1908854-irs-forms-availability-table-for-turbotax-individual-perso...