If you hold a Work Permit and wish to apply for an S Pass, first ensure that you are eligible for the S Pass by using the S Pass self-assessment tool. If you meet the requirements, your employer can then apply for an S Pass for you. Do note that your employer has to meet the quota requirements too. (Tip : Your employer should apply for the S Pass as early as possible.)
You can remain in Singapore while the application is being made, as long as your Work Permit is valid. Your employer doesn’t have to cancel the Work Permit before the S Pass is approved. If your Work Permit is expiring before you get the S Pass application outcome, your employer can request to extend your Work Permit. The extension is subject to MOM’s approval.