Stabilize Medicaid and CHIP Coverage Act of 2015

Amends title XIX (Medicaid) of the Social Security Act (SSAct) to require a state Medicaid plan to provide 12-month continuous enrollment for an eligible individual, regardless of age.

Directs the Secretary of Health and Human Services to: (1) identify methods that promote the retention of individuals who are enrolled under the state plan or under a waiver of such plan and remain eligible for medical assistance beyond the 12-month period, (2) actively promote the adoption of such enrollment retention methods by states, (3) publish the procedures that states are expected to use to provide annual enrollment and retention reports, and (4) publish annually enrollment and retention performance results for all states.

Amends SSAct title XXI (State Children's Health Insurance) (CHIP) to: (1) require a state CHIP plan also to provide 12-month continuous enrollment for an eligible individual, and (2) prohibit eligibility standards from applying a waiting period for a targeted low-income child (including a child provided dental-only supplemental coverage).

Amends SSAct title XIX to allow a state to qualify for performance bonuses for the enrollment and retention in Medicaid of certain low-income individuals.

Directs the Secretary to make bonus payments to eligible states adopting certain policies and demonstrating improvement in the continuity of enrollment.