Working for another company on H1B receipt without quitting the old one.

[KanAnd]

I work for company A with H1B and I got an offer from B. B is asking me to join on receipt. Is it possible to join B without quitting A? Is it legal taking an unpaid vacation and working with another company on H1B? Is it possible to work for both companies parallel without informing them?

[pontevecchio]

Unpaid vacations will result in bad consequences. If B wants to hire you part time, they can file a part time H1 subject to no objection from A.