(a) An insurer may make available a multi-tier program, with more than one rate level in the same company, for private passenger motor vehicle insurance in the voluntary market, provided that:

1. (1) the program and the insurer's business plan encourage depopulation of the assigned risk plan established by article fifty-three of this chapter;
2. (2) the program is based upon mutually exclusive underwriting rules per tier, to the extent feasible;
3. (3) credits and surcharges pursuant to an approved rating plan can be applied on a per tier basis; and
4. (4) the program conforms to regulations promulgated by the superintendent.

(b) For an insurer with an approved multi-tiering program, the provisions of subsection (f) of section three thousand four hundred twenty-five of this chapter shall apply in all respects, except that the two percent limitation set forth therein shall:

1. (1) not apply to any risk moved from a tier to a lower-rated tier; and
2. (2) be deemed to be three percent for risks moved from a tier to a higher-rated tier.