Medicare Advantage (MA) supplemental benefits offered at no or low premiums are a key value proposition for low-income beneficiaries. Despite nearly $20billion in rebate payments to MA plans for funding supplemental benefits, their quality or enrollee access is not monitored. Using 2018-19 Medicare Current Beneficiary Survey data linked to MA plan data, we found that regardless of plan benefit generosity, low-income beneficiaries were more likely to report dental, vision, and hearing unmet needs because of cost. Enrollment in plans with higher corresponding-year (that is, the same year as unmet need measurement) star ratings was associated with lower dental unmet need. Income-related disparities in dental unmet needs were lower in the highest-rated plans. However, prior-year star ratings that determined plan payments were not associated with unmet needs or disparities in those needs. Policy makers should consider monitoring supplemental benefits for equity and access, and they should assess the value added by quality bonus payments to high-rated plans for beneficiaries' access.