If you are in the United States and changing from one H-1B employer to another,
or adding additional H-1B employment (known as a concurrent petition), the federal regulations permit you to begin working for the new employer on the start date indicated on the petition we submitted on your behalf. This is commonly referred to as "Portability".
To verify you qualify for the Portability Rule, IFSS will place a sticker your I-797C receipt notice indicating your new work authorization expiration dates under the Portability Rule. You may show the original receipt notice as part of your I-9 verification documentation. Additionally, the Wisconsin DMV will recognize the Portability Rule as well if you need to apply for or renew your Wisconsin driver license.
Legal citation:
8 CFR 214.2(h)(2)(i)(H)