My company filed my perm application in march 2009 and We did`nt heard any thing from uscis. My H1 is expiring(Max-6 years) in March 2010. My question is when I can file for H1 extension?
You can apply for H-1 extension 6 months ahead. But the start date cannot be earlier than March 2010 (when the one year pendency/filing of PERM is reached). You can also get an H-1 extension when your I-140 is approved (if your priority date is not current).