From form 1099B worksheet - capital asset sales wksht(1) cost or adjusted basis (positive amounts only) must be entered

if the cost is blank a number needs to be entered even if it is zero. This would be true for a short sale of an option that expired. Forget about your 1099-B you have to see what's in Turbotax.

sale number 6 

5 calls xyz exp 10/15/2023

A (8949 box)

05/01/2021 (date sold) 

10/15/2023 (date acquired)

500.00 (sales price)

?           (cost or other basis  - can't be blank)

now my broker does something weird (i just leave it)  for the date sold it uses the date the short option expired or was purchased to close

for the acquisition date it uses the date of the short sale

to prevent long-term treatment for a short sale it puts it in the Type A category short-term basis and proceeds reported to iRS though it looks to the iRS as long-term. never had an issue or notice from the iRS about this. 

I did go in for several short sales and show the date the position was opened as the date sold and the date the position was closed as the date acquired. ran final review and had no errors.