You “ported” (transferred) your H-1B approval to a new employer, but the H-1B visa stamp in your passport is for a prior employer – and you need to travel. The stamp is unexpired – can you use your old visa stamp for travel with your new employer?
Yes, it is possible to use the old visa stamp for new employment, but care must be taken. Normally, presenting an H-1B visa stamp for Employer A will create the assumption that the foreign national is entering the U.S. to work for Employer A. This is the case even if a petition has been approved to transfer the foreign national’s H-1B status to Employer B. In fact, once an H-1B transfer (port) petition is approved, the foreign national is authorized to work only for the new employer (Employer B), and the authorization to work for the old employer (Employer A) ends. As a result, re-entering the U.S. with the old visa stamp can “re-trigger” the authorization for Employer A, and suspend the authorization to work for the Employer B.
To avoid this result, the foreign national must present the new H-1B approval (the approval of the transfer) to the CBP at the same time as the old visa stamp is presented. This is the only way to ensure that the CBP understands who the foreign national will work for. Further, this is the only way to ensure that the admission is granted for the full period of the new approval, rather than the (presumably shorter) authorization of the old visa petition.
To do this, the foreign national must be “otherwise admissible” – in other words, they cannot have violated their status. The foreign national also must have a valid passport, have an unexpired visa stamp, can establish prior admission to the U.S. in H-1B status, and, of course, provide proof of the new approval. Often, the CBP also will want to see a letter from the current employer verifying the ongoing employment.
 Michael A. Pearson, Executive Associate Commissioner, Office of Field Operations for the USCIS on January 29, 2001, entitled “INS Directive on Travel and AC21.
Next: New Approval, New Status, Overseas Travel