This page list all the Income Type and whether they affect the Socso, EPF, PCB, EIS. From the above screen the Backpay Income Type does not affect all the statutory contribution.
To enable the Backpay Income type to be affected, please check all the boxes based on the column needed. After checking Socso, EPF, PCB and EIS for Backpay and click the submit button at the bottom of this page, you will see that the data is saved as below.