If you have STEM extension programme you must apply for STEM Extension programme.It will give

a status for 2 further years

Navigating the "cap gap" period can be tricky. If your OPT expires before your H-1B is approved, you may qualify for an automatic extension of your work authorization, provided your employer filed an H-1B petition requesting a change of status before your OPT ends. This extension lasts until the H-1B start date (October 1st) or until the petition is rejected, denied, or withdrawn.

If your H-1B is approved after your OPT expires, you can stay in the U.S. for 60 days but cannot work during that time. If the H-1B is approved before your OPT expires, your work authorization continues without interruption.

Disclaimer: This is general information, not legal advice. I'm an immigration attorney, but I'm not your attorney until an attorney-client relationship is established. For personalized advice, call me at (888) 315-4828 for a consultation or contact a qualified immigration attorney.

If your OPT expires before your H-1B status begins (typically on October 1), you can benefit from the automatic “cap-gap” extension. This maintains your F-1 status and work authorization until the H-1B status takes effect