If it’s for shares bought before 2011, they don’t even have the basis. (They can detect that you had a sale for which they got a 1099-B but you didn’t list on

If it’s for shares bought before 2011, they don’t even have the basis. (They can detect that you had a sale for which they got a 1099-B but you didn’t list on your Schedule D. That doesn’t mean they have enough information to fix it.)