Sure, getting your bonus bought out provides some superficial relief for this problem. But if your next employer thinks that your value is high enough to buy out your bonus, they likely think that independent of the current date (modulo a special case where your value /now/ is significantly higher than it would be in another quarter or whatever). Your next employer gets no value from the fact that you're leaving previous money on the table; if they offer to buy out a bonus, stay, get that bonus, then remind them that they thought you had that additional value and you'll take at as a signing bonus now, thank you very much.