110 STAT. 4320 CONCURRENT RESOLUTIONS—APR. 16, 1996 (b)), the emplGying office may not designate leave as FMLA leave retroactively, and may designate only prospectively as of the date of notification to the employee of the designation. In such circumstances, the employee is subject to the fiili protections of the FMLA, as made applicable by the CAA, but none of the absence preceding the notice to the employee of the designation may be counted against the employee's 12-week FMLA leave entitlement. (d) If the employing office learns that leave is for an FMLA purpose after leave has begun, such as when an employee gives notice of the need for an extension of the paid leave with unpaid FMLA leave, the entire or some portion of the paid leave period may be retroactively counted as FMLA leave, to the extent that the leave period qualified as FMLA leave. For example, an employee is granted two weeks paid vacation leave for a skiing trip. In mid-week of the second week, the employee contacts the employing office for an extension of leave as unpaid leave and advises that at the beginning of the second week of paid vacation leave the employee suffered a severe accident requiring hospitalization. The employing office may notify the employee that both the extension and the second week of paid vacation leave (from the date of the injury) is designated as FMLA leave. On the other hand, when the employee takes sick leave that turns into a serious health condition (e.g., bronchitis that turns into bronchial pneumonia) and the employee gives notice of the need for an extension of leave, the entire period of the serious health condition may be counted as FMLA leave. (e) Employing offices may not designate leave as FMLA leave after the employee has returned to work with two exceptions: (1) If the employee was absent for an FMLA reason and the employing office did not learn the reason for the absence until the employee's return (e.g., where the employee was absent for only a brief period), the employing office may, upon the employee's return to work, promptly (within two business days of the employee's return to work) designate the leave retroactively with appropriate notice to the employee. If leave is taken for an FMLA reason but the employing office was not aware of the reason, and the employee desires that the leave be counted as FMLA leave, the employee must notify the employing office within two business days of returning to work of the reason for the leave. In the absence of such timely notification by the employee, the employee may not subsequently assert FMLA protections for the absence. (2) If the employing office knows the reason for the leave but has not been able to confirm that the leave qualifies under FMLA, or where the employing office has requested medical certification which has not yet been received or the parties are in the process of obtaining a second or third medical opinion, the employing office should make a preliminary designation, and so notify the employee, at the time leave begins, or as soon as the reason for the leave becomes known. Upon receipt of the requisite information from the employee or of the medical certification which confirms the leave is for an FMLA reason, the preliminary designation becomes final. If the medical certifications fail to confirm that the reason for the absence was an FMLA reason, the employing office must withdraw the designation (with written notice to the employee).