The term "wages" does not include any payment (other than vacation or sick pay) made by an employer to an employee after the calendar month in which the employee attains age 65, if-
Vacation or sick pay is not within this exclusion from wages. If the employee does any work for the employer in the period for which the payment is made, no remuneration paid by such employer to such employee with respect to such period is within this exclusion from wages. For example, if employee A, who attained the age of 65 in January 1955, is employed by the X Company on a stand-by basis and is paid $200 by the X Company for being subject to call during the month of February 1955 and an additional $25 for work performed for the X Company on one day in February 1955, then none of the $225 is excluded from wages under this exception.
26 C.F.R. §31.3306(b)(8)-1