Expense reports that have reached the LOCKED or EXTRACTED status can no longer be modified. However, should you have an expense report having one or more line items that have been incorrectly entered and approved, you can enter a ”correcting expense report”.
The correcting expense report is simply a new expense report created to contain a line item exactly the same as the original incorrect line item in an expense report except that the amount is a negative (to offset the original amount). A new line item may then be entered to supply the correct amount, project type, etc.
You can also void expense reports even after a financial post (see People List -> Voiding Expense Reports).