Tax clearance is not required for the following categories of employees/scenario. If your employees fall under these categories/scenarios, you do not need to complete Form IR21 but you must submit the employee's income details to IRAS using Form IR8A or through the Auto Inclusion Scheme by 1 Mar.
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- The employee ceases to work for you in Singapore; or
- The employee starts an overseas posting; or
- The employee leaves Singapore for any period exceeding three months.
source : https://www.iras.gov.sg