If the city permanently discontinues its contributions to the plan without terminating the plan, the assets of the pension fund, as of the last day of the plan year in which such discontinuance becomes effective, shall be deemed to be vested in the members of the plan on such date in the manner described in section 18-60, except that no distribution of assets shall be made in accordance with such vested right until the member entitled thereto retires or terminates his employment with the city. For the purposes of this section, the city shall be deemed to have permanently discontinued contributions if as of the last day of any plan year the unfunded liability is determined to be greater than the sum of its unfunded liabilities as of the effective date of the plan and any additional unfunded liabilities due to subsequent plan amendment or change in actuarial assumptions.
(Code 1958, § 21-28.1)