86.1570.  Offset to workers' compensation payments — member's percentage defined. — 1.  Any periodic payment, excluding payments for medical treatment, which may be paid or payable by cities under the provisions of any workers' compensation or similar law to a member or to the dependents of a member on account of any disability or death shall be offset against any benefits payable to the recipient of the workers' compensation payments from funds provided by cities under the provisions of sections 86.1310 to 86.1640 on account of the same disability or death.  However, in no event shall the amount paid from funds under the provisions of sections 86.1310 to 86.1640 be less than the amount which represents the member's percentage, as defined in this section, of total benefits payable under sections 86.1310 to 86.1640, before any offset for workers' compensation benefits.

  2.  Any lump sum amount, excluding payments for medical treatments, which may be paid or payable by cities under the provisions of any workers' compensation or similar law to a member or to the dependents of a member on account of any disability or death shall be offset against any benefits payable from funds provided by cities under the provisions of sections 86.1310 to 86.1640 on account of the same disability or death.  The amounts by which each periodic payment made under the provisions of sections 86.1310 to 86.1640 is offset or reduced shall be computed as the periodic amount necessary to amortize as an annuity over the period of time represented by the respective workers' compensation benefits the total amount of the lump sum settlement received as a workers' compensation benefit by a beneficiary of the retirement system.  Such computation shall be based upon the same interest rate and mortality assumptions as used for the retirement system at the time of such computation.  However, in no event shall the amount paid from funds under the provisions of sections 86.1310 to 86.1640 be less than the amount which represents the member's percentage, as defined in this section, of total benefits payable under sections 86.1310 to 86.1640, before any offset for workers' compensation benefits.

  3.  As used in this section, the term "member's percentage" shall be the fraction of which the numerator is the percentage of compensation contributed by a working member to the retirement pension system under section 86.1400 during the pay period immediately preceding such member's death or disability which created entitlement to benefits and the denominator is the sum of percentages of a member's compensation contributed by a working member under section 86.1400 and the city under section 86.1390 to the retirement pension system during such pay period.  Such percentage shall identify the portion of any benefits due under the provisions of sections 86.1310 to 86.1640 which is deemed to have been provided by the member's own contributions.