Any monies which an employee is entitled to upon termination--including unused PTO which the employee had a right to be paid for at the end of employment--must be paid to the employee unless and only if--1) The employee consented or agreed to allow the employer to withhold part or all of it (such as to reimburse for tuition the employer had provided, but which the employee has to repay); or2) The employee failed to provide some necessary documentation, needed to pay the amounts (e.g. a final time sheet, for final wages), in which case the employer can hold onto the money until the employee does the paperwork.Note that retirement monies may be a little different--pensions, 401(k)s, etc. have their own rules about when and how you vest (each employer can, to a large degree, set its own vesting rules), when and how you are entitled to be paid the funds, etc. There is no general answer about employee eligibility for retirement monies, but rather you must reference the specific plan.