I want to go to US with my husband on H4 in January. My employer is ready to file my h1b visa in April 2013. Do i need to come back to file my H1b visa? Or my employer can file it while I am in US on H4?
You can stay in US and file H1
You can file change of status from H4 to H1B. Many people do that. You will not need to come back.
But if you come back to india after H1B is approved, you will have to get passport stamped with H1B visa.