In case it helps anyone, two things I've learned about line 2b on the Medical Expenses Worksheet.
1) If YOUR math and TT's math differ by a few dollars, note that TT takes EACH month from your 1095-A entries and ROUNDS it up/down, as appropriate, to generate the values it populates into Form 8962.
2) At least on the DeskTop version, Right clicking on the value TT places at line 2b of the Medical Expenses worksheet and then hitting "Data Source" brings up a dialogue box that tells you more about how TT does the math. TT used to do a better job making the math more visible to us analytical types that want to see what's behind the Wizard of Oz curtain:-)
