Get your taxes done using TurboTax

@buzhidaoist Then TT allows you to enter an adjustment code and change the basis.  The only difference is that both the old and new basis are shown.

 

There's undoubtedly a way to do it in the interview process, but in Forms mode, go to the 1099-B with the incorrect transaction.  Double-click on the 'Description' (or click on any of the magnifying glass icons that show up when you click on any field) and a "Capital Gain (Loss) Adjustments Worksheet" opens up.  In part III, Specific Adjustments, check the first box (1099-B reports and incorrect basis) and enter the right number.

**Say "Thanks" by clicking the thumb icon in a post
**Note also, I'm not a Tax Preparer/CPA. Just a volunteer, seasoned, TurboTax user.
Use any advice accordingly!