My company promised me a ₹1 lakh performance bonus for last year. But they say I have to pay it back if I leave before March 2015. They even got me to sign a letter confirming this. Can I challenge this if I decide to leave before then?

Under Indian law, such a clause requiring you to repay a performance bonus upon leaving before a certain date is likely to be unenforceable as it is considered a penalty clause. You can challenge this provision and argue that the bonus was earned and should not be clawed back.