I-140 H1B Extension Beyond 6years

H1B the non-immigrant visa is sponsored by employers to employees working with their firm on a full-time basis. I-140 is the change of status to permanent to Permanent residency and it is the second stage in processing Permanent Resident Card, popularly called the green card in USA.
How long can I stay in USA under H1B status?
When an employer files for a H1B visa it is approved for 3 years(in today's scenario USCIS has more restrictions and gives approval for less than one year.This is a general discussion..so lets ignore that). We can go for an H1B extension and have it extended for 3 more years.
Note : Whenever you are going for a H1B extension it is 3 years from date of filing the extension petition. If you have H1B visa in first tenure about to be expired by September 2010 (say for eg) and you file for H1B extension by April 2010, your extension is going to be April 2010 + 3 years --> April 2013. Instead if you start it by June you will save 2 more months and have it extended until June 2013. Keep this simple tip in mind and have proper consultation with attorney before proceeding further.
As a whole in a H1B visa we can stay for 3+3 -- > 6 years
What if I want to stay beyond 6 years?
We need to request employers to file for permanent residency status. This entire process called teh Green card processing is a 3 stage process
1) PERM (or) Labour filing
2) I-140 - Change of status - We'll be discussing about this in out post
3) I-485
If you have your PERM filed and the application is in pending, we can have H1B extended for 1 more year - 7 years of stay
If you have an approved I-140 you can extend it in terms of 3 years every time we go for an extension - After 6 years + 3 years - 9 years and it goes on.
Can I change my job with an approved I-140?
It is possible to change jobs from employer A to employer B. Only criteria is that employer A should not revoke the I-140. Also, we can retain the original priority date in which PERM/labour certificate was filed with the first employer.