i would find it ridiculous to have such arrangement. most companies opt to pay by 3-4 months installment, this 12 months thingy is overboard. it's a reward after a year of hard work, and yet you have to wait. the hefty income tax imposed on my bonus is already driving me crazy, if to top with one, i will be exploited.

the company rational of retaining the staffs and create a balance of resignation ratio after bonus payout is not realistic, when one wish to leave, it's just a matter of time.