Generally, when your non-Singapore Citizen employee ceases employment with you in Singapore, goes on an overseas posting or plans to leave Singapore for more than three months, you must notify IRAS at least one month in advance and withhold all monies due to the employee from the date you are aware of his impending cessation of employment or departure from Singapore. The type of pass your employee holds (including long-term visit pass and dependant's pass) does not affect the tax clearance requirement.

For details, please refer to Tax Clearance for Employees. You may also use the Tax Clearance Calculator (XLS, 115KB) to find out whether tax clearance is required for your employee and the guide (PDF, 1.9MB) for step-by-step filing instructions. 

This information is sourced from IRAS.