You can allow employees to choose whether or not an expense is marked as reimburseable. If you don’t enable the Reimburse column at the system level, all expenses are marked as reimburseable by default, since this is the most commonly-used option.
To allow employees to select whether individual expenses are reimbursed or not:
Note that employees can also hide this column using the Settings button on individual expense sheets.
This option will retain the settings in place at the time it was hidden. So, if the user disabled the Reimburse check box for a field, then hid that field, it will remain non-reimburseable, even if the option is now hidden.