A person who is receiving the exemption contained in RCW 84.36.381 through 84.36.389 shall be exempt from any legal obligation to pay a portion of the charge imposed by this chapter according to the following.

(1) A person who meets the income limitation contained in RCW 84.36.381(5)(a) and does not meet the income limitation contained in RCW 84.36.381(5)(b) (i) or (ii) shall be exempt from twenty-five percent of the charge.

(2) A person who meets the income limitation contained in RCW 84.36.381(5)(b)(i) shall be exempt from fifty percent of the charge.

(3) A person who meets the income limitation contained in RCW 84.36.381(5)(b)(ii) shall be exempt from seventy-five percent of the charge.