Medicare & Medicaid Glossary

A

ABD — Aged, Blind, and Disabled (Medicaid) {#abd}

The Medicaid eligibility pathway for adults 65+ or with a qualifying disability. Uses much stricter income limits (~SSI Federal Benefit Rate) AND a $2,000 individual / $3,000 couple asset limit. Different from ACA-expansion Medicaid (which has no asset test).

ACA — Affordable Care Act {#aca}

2010 law that created the Medicaid expansion option for states (138% FPL for adults under 65 in expansion states), the marketplaces with premium tax credits, and protections like guaranteed-issue health insurance.

AEP — Annual Enrollment Period (Medicare) {#aep}

October 15 – December 7 every year. Switch Advantage plans, switch Part D plans, drop Advantage to return to Original Medicare. Changes take effect January 1.

C

CHIP — Children’s Health Insurance Program {#chip}

Federal-state program for children in families above Medicaid limits but below ACA-marketplace affordability thresholds — usually 200%–300% of FPL.

CMS — Centers for Medicare and Medicaid Services {#cms}

The federal agency administering Medicare, Medicaid, and CHIP. Sub-agency of HHS, headquartered in Baltimore.

COBRA {#cobra}

The Consolidated Omnibus Budget Reconciliation Act lets you keep employer coverage for 18 months after job loss. Critical Medicare trap: COBRA is NOT considered creditable coverage for Medicare’s late-enrollment penalty. If you turn 65 while on COBRA and don’t enroll in Part B in time, the penalty applies for life.

Creditable Coverage {#creditable-coverage}

Drug coverage that meets or exceeds standard Part D — used to avoid the Part D late-enrollment penalty. Plans must send a yearly notice telling you whether their coverage is creditable.

D

Donut Hole — Coverage Gap {#donut-hole}

Old Part D phase between initial coverage and catastrophic where beneficiaries paid more out of pocket. Eliminated by the Inflation Reduction Act for 2025+. Replaced by a hard out-of-pocket cap ($2,100 in 2026).

Dual-Eligible — FBDE / SLMB+ / QMB+ {#dual-eligible}

People who qualify for both Medicare AND Medicaid. Several sub-categories: FBDE (Full-Benefit Dual-Eligible) gets full Medicaid plus Medicare; partial dual-eligibles get help with Medicare premiums and cost-sharing through the Medicare Savings Programs.

F

FPL — Federal Poverty Level {#fpl}

The annual income line published by HHS used for Medicaid, ACA subsidies, and many other programs. 2026 FPL: $15,960 single, $21,600 couple, +$5,640 per additional person (48 contiguous states + DC; AK and HI higher).

FBDE — Full-Benefit Dual-Eligible {#fbde}

Medicare beneficiary who also qualifies for full Medicaid. Medicare pays primary; Medicaid covers Part B premiums, cost-sharing, and benefits Medicare doesn’t (long-term care, dental, vision, transportation in many states).

FMAP — Federal Medical Assistance Percentage {#fmap}

The share of Medicaid spending the federal government pays — varies by state from 50% (wealthy states) to 77% (poorest), with bumps for ACA expansion (90%) and CHIP. Determines how much skin a state has in the game.

G

GEP — General Enrollment Period (Medicare) {#gep}

January 1 – March 31 each year for people who missed their IEP and don’t qualify for an SEP. Coverage starts the month AFTER you sign up. Late-enrollment penalty applies.

I

IEP — Initial Enrollment Period (Medicare) {#iep}

The 7-month window centered on the month you turn 65 — 3 months before, the birthday month, and 3 months after. The cleanest way to enroll without penalty.

IRMAA — Income-Related Monthly Adjustment Amount {#irmaa}

The income-based surcharge added to Medicare Part B and Part D premiums for higher-income beneficiaries. Based on your tax return from 2 years prior. Five surcharge brackets above the base. Use the IRMAA Calculator.

L

LIS — Low-Income Subsidy / Extra Help {#lis}

Federal program that helps people with limited income pay Part D premiums, deductibles, and copays. 2026 income limit: 150% FPL.

LTC / LTSS — Long-Term Services and Supports {#ltss}

Care for people who can’t perform Activities of Daily Living independently. Medicare covers very little; Medicaid is the largest funder of nursing home care in the U.S.

M

MA-PD — Medicare Advantage Prescription Drug plan {#ma-pd}

A Medicare Advantage plan that includes Part D drug coverage. Most MA plans are MA-PDs. The alternative is a stand-alone Part D plan paired with Original Medicare or a non-drug MA plan.

MAGI — Modified Adjusted Gross Income {#magi}

AGI plus tax-exempt interest plus a few add-backs. The basis for Medicare IRMAA brackets, ACA marketplace subsidies, and ACA-expansion Medicaid eligibility.

Medigap — Medicare Supplement Insurance {#medigap}

Private insurance that fills gaps in Original Medicare (Part A and B deductibles, coinsurance). Plans labeled A through N; Plan G is the most common new-buyer plan post-2020. Cannot be used with Medicare Advantage.

MMMNA — Minimum Monthly Maintenance Needs Allowance {#mmmna}

The minimum income protected for the community spouse when the other spouse is on Medicaid for nursing home care. 2026 federal floor is around $2,555/month; many states allow higher.

MOOP — Maximum Out-Of-Pocket {#moop}

The annual cap on a Medicare Advantage plan’s cost-sharing. 2026 federal cap: $9,350 in-network, $14,000 in + out-of-network. Plans can offer lower caps as a competitive feature.

MSP — Medicare Savings Program {#msp}

State-administered programs that pay Medicare premiums and cost-sharing for low-income beneficiaries. Four levels: QMB, SLMB, QI, QDWI. See the 2026 Medicare Rates page for income limits.

P

Part A {#part-a}

Hospital insurance. Most people pay no premium because they (or a spouse) worked 40+ quarters in Medicare-covered employment. Covers inpatient hospital, skilled nursing facility, hospice, and limited home health.

Part B {#part-b}

Medical insurance. Doctor visits, outpatient care, durable medical equipment, preventive care. Most beneficiaries pay $202.90/month in 2026; higher incomes pay IRMAA surcharges.

Part C — Medicare Advantage {#part-c}

Private-plan alternative to Original Medicare. Combines Part A + B (and usually D), often with additional benefits like dental, vision, hearing, gym membership, transportation. Network restrictions usually apply.

Part D — Prescription Drug Coverage {#part-d}

Outpatient prescription drug coverage. Must be elected — Original Medicare does not include drugs. Late-enrollment penalty of 1% per month without creditable coverage applies for life.

POMS — Program Operations Manual System {#poms}

SSA’s official program manual — also covers Medicare premium and IRMAA adjudication rules. Authoritative for how SSA actually decides cases.

Q

QMB — Qualified Medicare Beneficiary {#qmb}

The most generous of the Medicare Savings Programs. Pays Medicare Part A premium (if any), Part B premium, deductibles, and all cost-sharing. 2026 income limit for single: $1,415/month.

S

SEP — Special Enrollment Period (Medicare) {#sep}

A right to enroll in Medicare outside the IEP/GEP because of a qualifying event — most commonly losing employer coverage. No late-enrollment penalty when used in time.

SHIP — State Health Insurance Assistance Program {#ship}

Federally-funded, state-administered free Medicare counseling. Every state has one. The most-overlooked free help in the entire program.

SLMB — Specified Low-Income Medicare Beneficiary {#slmb}

Medicare Savings Program tier above QMB but below QI. Pays Part B premium. 2026 income limit: $1,695/month single.

SNF — Skilled Nursing Facility {#snf}

Short-term post-hospital rehab covered by Medicare Part A — first 20 days free, days 21–100 with daily coinsurance, then no coverage. Different from nursing home care, which Medicare does NOT cover long-term.

SSA — Social Security Administration {#ssa}

Administers Social Security AND Medicare enrollment + IRMAA determinations. You typically interact with SSA, not CMS, when enrolling in Medicare or appealing IRMAA.