Thanks @MaryM428 , this is the conclusion I came to after wasting many hours looking for answers online, at last year's taxes, and IRS instructions for form 8962. Following the answer from the TurboTax 2020 software prompts for form 1095-A could result in significantly underreporting household MAGI as they refer only to some of the potential modifications (guessing it's often $0) to AGI rather than providing the required MAGI value itself. Ironically, TurboTax Premier software for 2019 had this right and caused me to question the dependent MAGI calculation this year- that and the fact that there is no line 8b on the 2020 1040 form. It's disconcerting to me that even this late in the game, Intuit hasn't updated this bug.
