I would hope that the Online product runs the same on either Windows or Mac - that's up to the browser. The desktop products do have some variations between Mac and Windows.
Yes, excess carryover appears on line 2 of the 8889...as of the first week of February of 2024. Prior to that the carryover was invisibly on Line 2 (i.e., it was part of the calculations on the 8889, just not printed) for many years.
Why? Because the IRS never provided any instructions on how to handle the carryover. It had to be on the 8889 in the first 13 lines, in order for other things to work, but the IRS never said where.
Now, the IRS rejects e-files with no entry on line 2 (8889), so TurboTax had to start printing the carryover there...even though this conflicts with the printed IRS instructions.
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