What is my US immigration status if I leave my H-1B job?

If you leave your job under H1B and you leave the job you loose your H1B status. If you filed your adjustment while in valid H1B status you are an adjustment applicant and can continue to be in US while awaiting your decision. However recently there have been reports of adjustment applications who have overstayed their visa being detained by ICE.

If your adjustment of status is pending, you are in a “period of stay authorized by the Attorney General” but this is not a status. To maintain status, you would need to file an I-539 to change to F-1 with I-20 from the school, pay SEVIS fee etc.

If your adjustment of status (AOS) was filed while your H1B is valid, you are authorized to stay in the U.S. during the AOS pendency. You would need to have your AOS-based EAD and travel document before you can work or travel based on your pending AOS. You are allowed to study while you are waiting for your AOS to be approved. Please note that if you decide not to maintain your H1B status until your AOS is approved and USCIS denies your AOS, you will be required to leave the U.S. immediately.

If your H-1B status terminates, and your Adjustment of Status application (which was properly filed) is pending, you will be in a period of authorized stay. This is not lawful immigration status but you will not accrue unlawful presence.

If your I-485 is pending, yes, you can still legally stay in the U.S. However, because you lost your H-1B, your legal status in the U.S. will be an issue if your I-485 is denied.