When you apply for coverage in the Health Insurance Marketplace, you have to estimate your expected income for the entire year. Whenever the estimate is off, sometimes you'll have to pay back any excess.
In certain situations, the repayment of excess Advanced Premium Tax Credit isn't limited to the amounts you're referring to. Different repayment limitations may apply, or there may be no repayment limitation in such circumstances.
Please see Excess APTC not limited to amounts in Table 5 in the Instructions for Form 8962 for more information.
The calculation Form 8962 is extremely complicated, even by IRS standards. See page 1 in the link for the computation.
