The term “employe,” as used in this act is declared to be synonymous with servant, and includes--

All natural persons who perform services for another for a valuable consideration, exclusive of persons subject to coverage under the Longshore and Harbor Workers' Compensation Act (44 Stat. 1424, 33 U.S.C. § 901 et seq.) or the Merchant Marine Act of 1920 (41 Stat. 988, 46 U.S.C. § 861 et seq.) or persons whose employment is casual in character and not in the regular course of the business of the employer, and exclusive of persons to whom articles or materials are given out to be made up, cleaned, washed, altered, ornamented, finished or repaired, or adapted for sale in the worker's own home, or on other premises, not under the control or management of the employer. Except as hereinafter provided in clause (c) of section 302 and sections 305 and 321,¹ every executive officer of a corporation elected or appointed in accordance with the charter and by-laws of the corporation, except elected officers of the Commonwealth or any of its political subdivisions, shall be an employe of the corporation. An executive officer of a for-profit corporation or an executive officer of a nonprofit corporation who serves voluntarily and without remuneration may, however, elect not to be an employe of the corporation for the purposes of this act. For purposes of this section, an executive officer of a for-profit corporation is an individual who has an ownership interest in the corporation, in the case of a Subchapter S corporation as defined by the act of March 4, 1971 (P.L. 6, No. 2),² known as the “Tax Reform Code of 1971,” or an ownership interest in the corporation of at least five per centum, in the case of a Subchapter C corporation as defined by the Tax Reform Code of 1971.