Why is TT Premier/Mac (up-to-date) calling cost-basis overrides I had to enter on IRS Form 8949 "errors" I need to fix by removing them (which will cost a LOT of $) ?

[larrywest42]

Box E is checked: the broker did NOT report the cost-basis (no idea why not), but did supply a "Supplemental Information" PDF that lists those values.  Since these "cost-basis" values — what I paid for the stocks — are almost the same as the sale prices, the tax implications are very costly.

[fanfare]

do not try to fix amounts with overrides. That's a no-no.

answer the step-by-step questions about basis and it will let you enter the correct basis.

IRS says:

For non-covered securities ( BOX B or E) showing zero (or wrong) basis, enter the correct basis yourself.
Use code "B" and put -0- in col (g).

That's how TurboTax will handle it.

@larrywest42