H1-B extension limits with an approved I-140

[duskandawn]

Hi All,

I wanted to know, if there any limit on the number of 3 years H1-B extension, after the initial 6 years of H1 is used up.

Here is my current scenario.

I have an approved I-140 with my previous employer. I switch to a new job 4 months back, but my new employer is not ready for the applying the GC right now.

My 6 years of H1-B completes in Oct 2014. And my new employer has already transferred my current H1-B valid till 2014.

Note: My I-140 wasn't used for getting an extension of 3 years.

My new employer wants to wait till 18 months of my job, before they can start my GC process all over again.

In order to do that, they will need to extend my H1-B with 3 years, based on my approved I-140.

So i am trying to find out, if during my 3 years H1-B extension, if i have to switch the job again, is there any provision of any further H1-B extensions, keeping in mind that my I-140 is valid,

or this 3 years extension is only a one time action which can be performed.

Any insights will be real helpful.

Thanks,