I come to US in 2010 with H1B Visa stamped which was valid till Dec 2011 (from Emp "A"), then last year employer "B" transfer and extended my H1B Visa which is valid till Dec 2014 and also i got new I-797 and I-94 which is valid till Dec 2014, but i haven't got a chance to travel to india so my passport still have visa stamp of my last employer "A" which is expired now. Last week i got an offer from one of the prestigious US firm and they are willing to transfer my H1B visa from Emploer "B", for that i have couple of questions: 1) Is expired stamped visa in passport is an issue, that too is from my last employer "A"? i some read that stamped visa should not be expired which gave me some fear. 2) When will I legally start working with new firm? Is it after i got transfer reciept from uscis or even before as well? 3) This is my thrid year in US and if i accept this offer this will gonna be my thrid employer, Is this any concerns in GC process? Thanks in advance!