As a EP holder trying to change jobs, when can I resign?
Wait for an In-Principal Approval (IPA) letter before resigning, because applying for an Employment Pass is not a walk in the park and we do not wish for our clients to be jobless after resigning before securing a new position.
There are tightening regulations on top of reduced quotas for issuing new Employment Passes. To be absolutely sure, wait for an IPA letter before resigning.
You may look into this article to understand some of the crucial reason why an Employment Pass is rejected.