This is a commonly asked question when it comes to year-end or when there is a leaver in a company: "Why there is a CPF top up contribution in this month payroll?". HR may encounter a CPF top up for their employee if the employee did not contribute the correct CPF in one of the previous months. This could happen if the user was performing manual CPF calculation prior to using our payroll software and the data provided during the data migration stage is incorrect.
source : www.cpf.gov.sg