(a) The monthly sum to be paid to each member eligible for disability received as a proximate result of service rendered in the performance of his or her duties under the provisions of section twenty-three-a of this article shall be equal to sixty percent of the monthly salary being received by such member, at the time he is so disabled, or the sum of $500 per month, whichever shall be greater: Provided, That the limitation provided in subsection (b) of this section is not exceeded.
(b) Effective for any member who becomes eligible for disability benefits on or after July 1, 1981, under the provisions of section twenty-three-a of this article, as a proximate result of service rendered in the performance of his duties within such departments, his monthly disability payment as provided in subsection (a) of this section shall not, when aggregated with the monthly amount of state workers' compensation, result in such disabled member receiving a total monthly income from such sources in excess of one hundred percent of the basic compensation which is paid to members holding the same position which such member held within such department at the time of his disability. Lump sum payments of state workers' compensation benefits shall not be considered for purposes of this subsection unless such lump sum payments represent commuted values of monthly state workers' compensation benefits.
(c) Any member who has served on active duty with the Armed Forces of the United States as described in section twenty-seven of this article, whether prior or subsequent to becoming a member of a paid police or fire department covered by the provisions of this article, and who, on July 1, 1986, is receiving or thereafter receives a disability pension, shall receive in addition to the sixty percent or minimum $500 authorized in subsection (a) of this section, one additional percent for each year served in active military duty, up to a maximum of four additional percent.
(d) Beginning on and after April 1, 1991, the monthly sum to be paid to a member who becomes eligible for total disability incurred not in the line of duty shall be the monthly benefit provided in subsection (a) of this section: Provided, That the limitation is subsection (b) of this section is not exceeded: Provided, however, That for any person receiving benefits under this subsection who is self-employed or employed by another, there shall be offset against said benefits the amount of $1 for each $3 of income derived from self-employment or employment by another: Provided further, That a person receiving disability benefits must file a certified copy of his or her tax return on or before the April 15 of each year to demonstrate either unemployment or income earned from self-employment or employment by another: And provided further, That there shall be no offset of benefit for any income derived from self-employment or employment by another when the annual total amount of such income is $7,500 or less.