(1) Subject to the provisions of this Constitution, the right of a person in the public service of the Federation to receive pension or gratuity shall be regulated by law.
(2) Any benefit to which a person is entitled in accordance with or under such law as is referred to in subsection (1) of this section shall not be withheld or altered to his disadvantage except to such extent as is permissible under any law, including the Code of Conduct.
(3) Pensions shall be reviewed every five years or together with any Federal civil service salary reviews, whichever is earlier.
(4) Pensions in respect of service in the public service of the Federation shall not be taxed.
Section 173 of the Constitution of the Federal Republic of Nigeria