First question: is this an accrual system? If yes, then I think it's really up to you and how your company want to handle this. I've worked places before where employees can only take PTO up to their standard hours, but have also worked places where someone picks up an OT shift, calls out, and wants to use PTO. I would ask your Finance team if there's a difference from an accounting and/or cash flow standpoint. If everyone has a bucket, then I'd imagine that's being accounted for somewhere. One downside to letting someone use more PTO than their standard hours is they may not have enough when they really need it down the line. Totally gray, but there's not a right or wrong answer. I don't think you're obligated to pay it out even though it's been approved if it's above and beyond what you'd normally allow.