See the instructions for Line 28 on a Form 8962 Premium Tax Credit when filing Married Filing Separately on page 15 and specifically Table 5 - https://www.irs.gov/pub/irs-pdf/i8962.pdf#page=15
Also see the instructions on page 5 for Married Filing Separately - https://www.irs.gov/pub/irs-pdf/i8962.pdf#page=5
Married filing separately. If you file as married filing separately and are not a victim of domestic abuse or spousal abandonment (see Exception 2—Victim of domestic abuse or spousal abandonment under Married taxpayers above), then you are not an applicable taxpayer and you cannot take the PTC. You must generally repay all of the APTC paid for a qualified health plan that covered only individuals in your tax family. If the policy also covered at least one individual in your spouse’s tax family, you must generally repay half of the APTC paid for the policy. See the instructions for Line 9, later.
However, the amount of APTC you have to repay may be limited. See the instructions for Line 28, later.
