Hello there, @David300.
Let me share some information on how you can handle the employee's payment in QuickBooks Online.
Editing an employee pay/P45 once a leaver is set is currently unavailable. At this time, you have to delete the leaver date and adjust it to add the last payment amount. To achieve the goal, you need to get help from QuickBooks Online Support Team. To contact support, select the Contact Us button from the Help menu. Or, check out the information from this link: Contact QuickBooks.
In case you need related resources while working with QuickBooks or payroll in the future, feel free to read the details from this link: QuickBooks Online Advanced Payroll Hub.
Post again if you have any other questions. I'm always here to help. Have a good day!
