Membership in a contributory retirement system is mandatory for nearly all Massachusetts public employees who are regularly employed on a full-time basis. If you are actively employed or on a leave of absence you may file your application to retire up to 120 days before you plan to retire.If you are actively employed or on a leave of absence you may file your application to retire within 120 days. Your retirement benefit is subject to federal income taxes. If you are a Massachusetts resident, however, your benefit is not subject to state income taxes. Massachusetts is a "non-Social Security" state. Massachusetts law requires all public retirees to file an affidavit verifying their eligibility to receive a retirement allowance. Is Spouse A Retiree of a Massachusetts State, City, Town or County Government? (1) Right to a Superannuation Retirement Allowance. How to Fill Out the Commonwealth Agency New Member Enrollment Form.