Help developing a Negative Formula that leverages a year end forecast result

Hi PS AM Gurus,

I am seeking help in developing a negative formula. I know support can't help me, this is a business requirement probably, but I had to give it a shot.

I need the negative formula or other mechanism to check what the forecasted balance is at the end of the year and only allow the employee to go that much negative. In other words, we accrue biweekly, but you can go negative as long as when the year ends the employee doesn't owe us anything. Now, I don't care if the employee leaves during that year because we handle it as a different matter. Is something like this even achievable and can you give me a hint?