Why is it saying I have to pay all the tax credit for healthcare back?

Are you referring to paying back the Premium Tax Credit (PTC) as reported on the 8962?

Generally, this happens when taxpayers make a low estimate to the Marketplace on the estimated income for the year at the beginning of the year when applying for the insurance, but by the end of the year, they ended up making more and disqualifying themselves for the credit.

What confuses taxpayers is that the repayment is not calculated on a month by month basis, but on an annual basis. So if by the end of the year, you go over 401 percent of the federal poverty level for your size family, then it is all disallowed.

What is the number on line 5 of the 8962?