You cannot start working for the new employer until USCIS issues a receipt notice for the H-1B transfer petition, unless you are currently maintaining H-1B status with another employer and your current employment is valid. USCIS requires proof that the petition is pending before you can lawfully begin work. Starting too early can create a violation that affects your status and future applications.

While you wait for the receipt notice, it’s essential to maintain valid status with your current employer if possible. Once the receipt is issued, you may begin working for the new employer if the petition qualifies for portability under H-1B regulations. Keeping copies of all filing documentation, including the receipt notice, is critical in case of any questions from USCIS or future applications.