How to Make an employee expense account mandatory ?

Summary:

When creating employee user account in Manage Users here we have a option to enter expense account and hence at present the column is non mandatory and here we want to make this column as mandatory and user shouldn't be able to save the employee until they have entered the default expense account

Content (required):

When creating employee user account in Manage Users here we have a option to enter expense account and hence at present the column is non mandatory and here we want to make this column as mandatory and user shouldn't be able to save the employee until they have entered the default expense account