When is vacation pay "payable" under final regs?

[Guest kjungkin]

Under the proposed regs 1.457-4(d) a deferral of compensation was allowed only if an agreement providing for the deferral was entered into before the begining of the month in which the amounts would be otherwise paid or payable and the participant is an employee in that month. The final regulations purportedly allow, under the special rule, for elections to defer to be made after the beginning of the month for sick, vacation & back pay provided the vacation pay would otherwise have been payable before the employee has a severance from service.

What is the case for an employee whose termination date is June 30, he severs his employment as of that date, but his accumulated sick pay, etc. is included in his final paycheck which is not paid to the now terminated employee until the next pay period which would be in July, due to administrative requirements? If he is entitled to the pay as of his date of termination, is this sufficient to deem the accumulated sick pay, etc. as "payable" before the severance from service?