4 Pa. Code § 612.9 – Effective date of resignation.

(a) When an employee gives notice of the effective date of resignation, the employee shall cease working for the appointing authority on the specified date.
(b) When an employee does not specify an effective date of resignation, the resignation shall take effect immediately.
(c) A resignation submitted during or at the termination of a leave of absence shall be effective on the date submitted.

This section cited in 4 Pa. Code § 614.2 (relating to notice of personnel actions).