I hope you're right for OP's sake, but these bonuses as described are common ways to get staff to stop rolling over so much, or to give bonus incentives for people to move from other cities, but you need a commitment back. It's 10/12 for that purpose. You're free to put the money in savings. The company wants you to stay for two years, if you accept it, though. Aren't "cliff" contracts usually described much differently, more clearly.
They made a commitment towards you and you broke it. Pay back the bonus and quit trying to dodge it. You said you left for a better job, so paying back this money shouldn't be a problem.
I agree the intent of it was probably 10/12. But, go ahead and argue that the clause means 10/24 since it isn't worded well. Of course, don't say anything at all unless they bring it up. What magnitude is it? Is it enough money to make paying a lawyer worthwhile?
Their interpretation is the same interpretation I would have had if I only read the clause you posted. You will likely lose, but you'll have to weigh the following: 1.) Potential cost/hassle of arguing (and likely losing) the terms of the agreement 2.) Repaying it in this calendar year means you will get a corrected W2 from the old employer so you can recoup your tax money when you file in 2015, as opposed to letting this issue bleed into 2015 and not being able to recoup the taxes until 2016 (I don't know taxes, though, so this is a guess on my part) vs. 1.) Possibility that HR turnover is high enough in the old company that the issue slips through the cracks 2.) Benefit of waiting and deferring the repayment (assuming they can't charge you interest) 3.) Small possibility of winning If you don't fight them too hard, you can probably work out a payment plan with them.
First off, it's "recoverable", not "must recover" or to that effect. So sit tight, let them ask it back, if at all they ask, as someone has pointed out. Second, check if there is a definition section at the beginning of the agreement, and if there is one, look for an explanation what "a 12 month basis is" or definitions that spell out stuff like that. Third, if nothing is spelled out in other section, 10/12 or 10/24 seems to be both plausible reading of that clause. You would argue 10/24, and they would argue 10/12, I think you would have higher chance of winning the argument.
Oh, well, that's that. I think their intention is clear then. Let them know you don't have the money in good faith, if they ask it back.
For what it's worth.....If you have to repay the part of the bonus, I think the employer is required to provide you with a corrected W-2 (W-2c) showing the new bonus amount. You should then be able to use that to file an amended return. Here is what the W-2c looks like: http://www.irs.gov/pub/irs-pdf/fw2c.pdf
