If at any time federal and/or State of Michigan laws shall permit inclusion of employee members under Title II of the Federal Social Security Act, the city council may amend the provisions of the retirement system to provide as follows:
(1) Employee members shall be covered under the provisions of the Federal Social Security Act to the extent permitted by laws of the State of Michigan and the United States Government.
(2) Employee member contributions shall thereupon be reduced by the amount of any social security tax which must thereafter be deducted from their pay as policemen or firemen of the city.
(3) Retirement benefits, death benefits and beneficiary's or dependent's benefits of all kinds under the retirement system may be reduced to the extent that corresponding benefits are payable under the federal social security program; provided, however, that deductions shall be provided for at least to the extent that the total cost of the retirement system to the City of Inkster (including federal social security taxes payable by the city) shall not be increased above the city cost requirements prior to participation in the federal social security program.