You may have to enter in an adjustment to update the amount of tax an employee has currently paid. If this is required for an employee, you can do this using an Adjustment transaction.
Choose Payroll, Transactions, Adjustments, Create or Modify.
Enter employee code.
Select 'E = Add New Pay - start with empty pay'.
Enter the tax adjustment in the Tax field.You may have to enter in an adjustment to update the amount of tax an employee has currently paid. If this is required for an employee, you can do this using an Adjustment transaction.
Accept (F9) to save the transaction.
Check the pay and process it as usual.