(1) (a) If the recipient of a disability retirement benefit is self-employed or employed in a position not covered by the retirement system, the recipient shall submit to the board an annual earnings statement, and any other documentation requested by the board, covering each month during which the recipient was self-employed or employed in the position.
(b) The amount of the recipient's retirement benefit must be reduced annually to an amount that, when added to the compensation earned by the recipient in that occupation, does not exceed the highest average compensation at the time of the recipient's retirement.
(c) The board shall annually adjust the recipient's highest average compensation as it was at the time of retirement by an inflationary factor equivalent to the consumer price index for all urban consumers if the recipient has been receiving a disability retirement benefit for more than 36 consecutive months.
(d) If the disability benefit recipient fails to submit the documentation as required under subsection (1)(a), the board may suspend the benefit payments until it receives the documentation.
(2) Benefit adjustments granted by the legislature may not be included in calculations required under this section.