25 Pa. Stat. § 2778.1
In all cases where under any law now or hereafter enacted, a special election is required to fill any vacancy in the office of member of the council or legislative body of any city, borough, town or township, such election shall be held on the day fixed in the writ for the special election or on such day as may be otherwise provided by such law, which day shall be within sixty (60) days after the issuance of the writ or after the happening of the vacancy, as the case may be, notwithstanding any provisions in such law requiring the special election to be held on an earlier day. This section shall not be construed as requiring a special election in any case where such election is not required under any law now or hereafter enacted.
25 P.S. § 2778.1