Hawaii bans stacking unless the insured buys the stacking option
Hawaii's rule is in HRS 431:10C-301. Subsection (c) prohibits stacking or aggregating UM and UIM coverage except as provided, and subsection (d) requires insurers to offer a stacking option. The underinsured definition is in 431:10C-103, and the no-fault tort threshold in 431:10C-306.
Read how stacked and unstacked coverage differ in Hawaii, check what subsections (c) and (d) require, or see how UM and UIM work under the no-fault law.