If your clawback is a deduction of the employee's net salary, eg, withholding tax, or Loan deduction, then this type of clawback will not reduce the CPF contribution of the month. I suggest you check those pay items, such as the Loan deduction, Tax withholding, miscellaneous deduction, and verify the cost rule that is mapped with. Do the same mapping of the cost rule with your clawback as follows:
Go to the Costing module and click Setup.
Select Cost Item and search for your existing Cost Item, eg, Loan deduction or withhold tax.
Click on the Cost Rule and verify the credit and debit GL Code that is tagged with
Then exit the window.
Click New and select Type as Pay Element and Confirm.
Click Save and select the credit and debit code based on your earlier and set the same.
If your clawback of basic salary affects the CPF contribution, then you need to check pay items such as No Pay Leave to verify the Cost rule of debit and credit code.