TN 49 (01-24)

HI 00815.006 Establishing State Payment of Medicare Part B Premiums (State Buy-In)

A. Overview

States, the District of Columbia (DC) and U.S. territories are responsible for ensuring that individuals included in their Buy-In Agreement with the Centers for Medicare & Medicaid Services (CMS) are enrolled in Part B buy-in. States, DC, specified U.S. territories, and CMS generally establish Part B buy-in for individuals through buy-in data exchange that involves the state, CMS, and the Social Security Administration (SSA).

In certain circumstances however, SSA should take steps to initiate Part B buy-in through the Public Welfare (PW) Accretion process for Medicaid beneficiaries who file a Medicare application and are eligible for a Medicaid group included in the state buy-in agreement. This most commonly occurs when a full-benefit Medicaid beneficiary newly qualifies for Medicare and applies for Medicare Part B before SSA has established Medicare entitlement on the Master Beneficiary Record (MBR) and before the state or territory has established Part B buy-in.


Full-benefit Medicaid coverage generally refers to coverage for a range of items and services, beyond coverage for Medicare premiums and cost-sharing, to which certain individuals are entitled when they qualify under certain Medicaid eligibility groups included in their state’s Medicaid State Plan filed with CMS.

B. Enrollment in Part B Buy-in by States, DC, Specified U.S Territories and CMS

The U.S. territories initiate Part B buy-in for all Medicaid beneficiaries included in the buy-in agreement.

States generally initiate Part B buy-in enrollment for Medicaid beneficiaries who do not receive Supplemental Security Income (SSI).

For Medicaid beneficiaries who receive SSI, Part B buy-in is generally initiated either by CMS or the state as outlined below.

1. CMS-Initiated Part B Buy-in for SSI recipients in Auto-Accrete States

Thirty-four states and Washington D.C. have an agreement with SSA under section 1634(a) of the Social Security Act. These states are referred to as “1634” states or “auto-accrete” states and are listed in HI 00815.030. CMS establishes Part B buy-in for SSI recipients in these states.


The exception is the state of Maryland which establishes Part B buy-in for SSI recipients itself.

  1. a. 

    Auto-accrete states have delegated authority to SSA to make Medicaid eligibility determinations for SSI recipients.

  2. b. 

    The Medicaid agency automatically enrolls the individual in Medicaid following data exchange with SSA.

  3. c. 

    SSA determines an individual eligible for SSI and establishes Medicare Part B eligibility.

  4. d. 

    CMS automatically initiates Part B buy-in for the individual through the buy-in data exchange.


    Ensure addresses are up-to-date within SSA systems.

2. State-Initiated Part B Buy-in for SSI recipients in Alert States (SSI Criteria States, 209(b) States)

Alternatively, states without a 1634 agreement establish Part B buy-in for SSI recipients on their own. States that have not entered into 1634 Agreements are referred to as “Alert States.” The Northern Marianas Islands, the only territory that has the SSI program, does not have a 1634 agreement with SSA and is considered an “alert state.”

In alert states, SSI recipients must submit a separate application to the Medicaid agency which determines eligibility for Medicaid benefits. CMS identifies SSI recipients who are Medicare-eligible, then the state determines Medicaid eligibility and initiates Part B buy-in enrollment for eligible individuals.

Alert states fall into two categories: SSI criteria states and 209(b) states.

  • SSI Criteria States – Consider SSI recipients as eligible for Medicaid upon completion of a Medicaid application.

  • 209(b) States – Apply more restrictive financial methodologies than SSI to determine eligibility for Medicaid.

See the CMS Manual for State Payment of Medicare Premiums, chapter 1, section and chapter 2, section 2.5.1.

C. Public Welfare Accretion Process for SSA to initiate Part B buy-in

SSA should initiate Part B buy-in through the Public Welfare (PW) accretion process for an individual whose Medicare entitlement is not yet present on the MBR, when the individual:

  • files an application for Medicare Part B;

  • is eligible for full-benefit Medicaid; and

  • is included in the state or territory’s buy-in agreement.


See section HI 00815.030 for processing instructions to establish Part B buy-in through the Public Welfare process.

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HI 00815.006 - Establishing State Payment of Medicare Part B Premiums (State Buy-In) - 01/12/2024
Batch run: 01/12/2024