You have to make a manual entry on one of the forms using the TurboTax desktop version installed on your own Mac or PC from a download. The adjustment can’t be made in TurboTax online.
The location of the adjustment is different from where it was described in that old article. Once you have installed TurboTax and are ready to make the adjustment, post back here and somebody can find the worksheet for you where the entry is made.
