GSIS Membership, compulsory or not?

Compulsory Membership

Under Section 3 of RA No. 8291, membership in the GSIS shall be compulsory for all government employees receiving compensation who have not reached the compulsory retirement age, irrespective of employment status, except members of the Armed Forces of the Philippines and the Philippine National Police and contractuals who have no employer and employee relationship with their agencies.

Coverage

GSIS covers all government workers irrespective of their employment status, except:

Members of the Judiciary and Constitutional Commissions who are covered by separated retirement laws;
Contractual employees who have no employee-employer relationship with their agencies; and
Uniformed members of the Armed Forces of the Philippines and the Philippine National Police, including the Bureau of Jail Management and Penology and the Bureau of Fire Protection.

Except for the members of the judiciary and constitutional commissions who shall have life insurance only, all members of the GSIS shall have life insurance, retirement and all other social security protection provided under RA No. 8291.

Source: Government Service Insurance System