I was covered under a marketplace plan through my Mom. Shared the plan with Mom and 1 brother. How do know what percentage to include? It's telling me I owe $900

[Mike9241]

if your mom is claiming you and/or your brother as dependents she reports for herself and anyone she claims as a dependent. If both of you then there is no policy allocation. In addition, she must include the modified AGI on her 8962 line 2b for each that she is claiming as a dependent. .

if it's a shared policy (she doesn't claim one or both of you), that portion of the 8962 must be completed. It's between your mom. and those she doesn't claim to agree on what % is to be allocated to each. the same % must be used for all columns for that month but different %'s can be used each month

I should point out that we know nothing about each of your tax situations which is crucial. What might be best for minimizing the PTC repayment may not be best from an overall tax standpoint. I don't think Turbotax can help you in determining what's best.