Your definitely going to have to sign a doc. What you need to figure out is how the payout works and if you get it even if they let you go prior to the timeframe. The last one i got was a big one but had lots of strings. 1/2 at 1 year, other half at year 2, once paid it was mine but if i got let go or left 1 day before payout i wouldnt get paid. Most of the time these bonus come because they are planing on major restructuring which probably includes your dept and maybe your role but they dont want everyone jumping ship and leaving them high and dry. Once the rumors start everyone starts looking for work. In my case they stayed true to their word. I stayed the 2 years, got a nice payday and then everyone most of us got let go. New it was coming and the payday made it easy to chill while looking for work. You boss may be telling you the truth but may also have job on the line and not know it. Long way of saying it doesnt cost you anything to take it. So take it but keep your ear to the ground and eyes open.