Select Chart of Setup from the Employer / Setup drop down menu. Click on the Payment Setup link in the Payment & Deduction section. You can find the list of pre-defined payment items that cannot be edited. If these do not meet your requirements you can create your own payment items.

Occurrence refers to how often the payment item will be applied to the employee's wages. If the occurrence is set as 'Recurring', the payment item will automatically be included in the employee's wages each and every time the employee's pay is calculated. If the occurrence is set as 'Non-Recurring', the payment item will only apply on a one-off basis in the next pay calculation you run for the employee and after that it will not automatically reappear. Further, click on the Save button to save the entered data.