(The Risks to Use the H1B Portability to Change Employer)

Question:

As a H1B employee in 2 years, I got a new and better job offer. I want to use the H1B portability to change employer when the new H1B petition is pending. Are there risks of using H1B portability in this way? 

Answer:

The risk in using H1B portability is that the H1B petition could be denied. This is especially true in a climate where the USCIS is scrutinizing H1B petitions closely, as well as changing their standards and expectations as to the proof needed to meet the legal requirements for an H1B petition. 

If you rely upon a pending H1B petition in order to stay in the United States and work, the denial of the H1B petition normally means that you will be out of status. This will create significant problems for you. The best way to avoid the risk of falling out of status due to reliance on H1B portability is to avoid using H1B portability. Therefore, you should go from approval to approval, and not depend solely on the pending H1B petition. This is often possible when using the premium processing service to expedite the processing of the new employer's H1B petition. 

also see http://www.greencardapply.com/question/question10/question10_0424.htm