In 2024, I liquated, in entirety, a non-retirement (taxable) mutual fund.
For that fund, I have both a "non-covered" dollar cost basis amount and a "covered" dollar cost basis amount.
Is it acceptable to add the non-covered dollar cost basis amount to the covered dollar cost basis amount to derive my total cost basis when reporting my sale?
You may get a separate 1099-B line for the Box E and Box D proceeds
If you acquired any shares in the 12 months prior to sale, those would appear under Box A.
You will receive a 1099-B from your broker itemizing your sale. Report the sale as reflected on your form and TurboTax will calculate your proper gain or loss.
"Is it acceptable to add the non-covered ..."
Yes.
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).
The correct basis on the sale is the amount you mentioned.
OR you could report non-covered and covered in separate transactions with the same Date Sold.
Either way is OK.
Date Acquired can be "Various".
You may get a separate 1099-B line for the Box E and Box D proceeds
If you acquired any shares in the 12 months prior to sale, those would appear under Box A.