Medicare, Medicaid, and ACA glossary

Every alphabet-soup acronym you'll encounter while picking a plan, with definitions written in plain English. Tap any cross-reference to jump to that entry.

AEP — Annual Enrollment Period: October 15 through December 7 every year. Anyone on Medicare can join, switch, or drop a Medicare Advantage or Part D plan. Changes take effect January 1.; See also: OEP, IEP
APTC — Advance Premium Tax Credit: The ACA Marketplace subsidy that lowers your monthly premium. The credit is based on household income vs. FPL and is paid directly to the insurer.; See also: FPL, CSR
BadgerCare Plus: Wisconsin's Medicaid program for low-income families, children, and pregnant residents. Covers adults up to 100% of FPL (Wisconsin did not expand Medicaid under the ACA).; See also: Medicaid, FPL
CSR — Cost-Sharing Reduction: Extra discount on Silver Marketplace plans for households 100–250% of FPL. Lowers deductibles, copays, and out-of-pocket maximums substantially.; See also: APTC, FPL
D-SNP — Dual Special Needs Plan: A Medicare Advantage plan that only enrolls people with both Medicare and Medicaid (or an MSP). Usually $0 premium with extras like OTC, dental, transportation. See our /dual-eligible page for the WI list.; See also: Dual-eligible, MSP, SNP
Deductible: What you pay out-of-pocket before insurance starts paying. Medicare Part A: $1,676 per benefit period in 2026. Part B: $283/yr. MA plans usually $0 medical / variable Part D.
Donut hole / coverage gap: The old gap in Medicare Part D coverage between the initial-coverage limit and the catastrophic threshold. Eliminated for 2025 onward by the Inflation Reduction Act — replaced with a $2,100 hard out-of-pocket cap in 2026.; See also: Part D, IRA
Dual-eligible: Someone with both Medicare and Medicaid (full dual) or Medicare and an MSP (partial dual). Eligible for D-SNPs and full LIS.; See also: D-SNP, MSP, LIS
EBD — Elderly, Blind, or Disabled Medicaid: Wisconsin Medicaid pathway for people 65+ or with a qualifying disability. Includes a 'spend-down' option (medical bills can lower countable income).; See also: Medicaid, SSI
Formulary: The list of drugs a Part D plan covers, organized into tiers. Lower-tier drugs (generic) cost less; higher tiers (specialty) cost more or require prior authorization.; See also: Part D, PA
FPL — Federal Poverty Level: Annual income guideline published by HHS each January. 2026 single-person: $15,960. Two-person: $21,640. BadgerCare, MSP, LIS, and Marketplace subsidies all key off % of FPL.
GEP — General Enrollment Period: January 1 – March 31. The fallback if you missed your IEP and don't have a Special Enrollment Period. Coverage starts the month after you sign up. Often comes with a Part B late-enrollment penalty.; See also: IEP, SEP
IEP — Initial Enrollment Period: Your 7-month window to sign up for Medicare around your 65th birthday — 3 months before, your birthday month, and 3 months after. Coverage start date depends on when in the window you enroll.; See also: GEP, SEP
IRA — Inflation Reduction Act (Medicare provisions): 2022 federal law that capped Part D out-of-pocket spending at $2,000 (2025) / $2,100 (2026), eliminated the donut hole, and capped insulin at $35/month. The IRA's enhanced ACA Marketplace subsidies expired Dec 31, 2025.; See also: Part D, Donut hole / coverage gap, APTC
LIS — Low-Income Subsidy ('Extra Help'): Federal Part D subsidy for Medicare beneficiaries with limited income (≤150% FPL post-IRA) and resources. Pays your Part D premium up to the regional benchmark, eliminates the deductible, and caps copays at nominal amounts.; See also: Part D, FPL, MSP
MA — Medicare Advantage (Part C): Private alternative to Original Medicare. Bundles Part A, Part B, and usually Part D into one plan, often with extras (dental, vision, OTC). Network-based — out-of-network care can cost you.; See also: MA-PD, Part D
MA-PD: A Medicare Advantage plan that includes Part D drug coverage. Most MA plans are MA-PDs.; See also: MA, Part D
MAGI — Modified Adjusted Gross Income: The income calculation used for ACA subsidies and most Medicaid programs. Roughly: AGI + tax-exempt interest + non-taxable Social Security + foreign income. Different from your tax-return AGI.
Medicaid: Joint federal-state program covering low-income individuals and families. In Wisconsin: BadgerCare Plus + Medicaid SSI + EBD + SeniorCare + Family Care.; See also: BadgerCare Plus, SSI, EBD
Medigap (Medicare Supplement): Private insurance that fills gaps in Original Medicare (Part A coinsurance, Part B coinsurance, etc.). Standardized plans by letter — Plan G and Plan N are the most popular for new enrollees. WI uses a different standardization scheme than most states.; See also: Original Medicare
MOOP / OOP max — Maximum out-of-pocket: The most you'll pay in a year for in-network covered services. After you hit MOOP, the plan pays 100%. Medicare Advantage federal cap for 2026: $9,250 in-network. Marketplace plans: varies by metal tier.
MSP — Medicare Savings Program: Medicaid-administered programs that pay Medicare premiums and (for QMB) cost-sharing for low-income beneficiaries. Three WI tiers: QMB (≤100% FPL), SLMB (100–120%), QI (120–135%). Asset-tested.; See also: Dual-eligible, FPL, LIS
OEP — MA Open Enrollment Period: January 1 – March 31. Lets people already on a Medicare Advantage plan switch to a different MA plan or drop MA for Original Medicare + a stand-alone Part D. Different from the AEP — narrower options.; See also: AEP
Original Medicare: Traditional fee-for-service Medicare = Part A + Part B. Pays providers directly. Often paired with a Medigap policy and a stand-alone Part D plan.; See also: Medigap (Medicare Supplement), Part D, MA
PA — Prior Authorization: Requirement that a plan approve a service or drug before it'll pay. Common on specialty drugs and expensive imaging. The #1 reason people skip prescribed medications on MA plans.; See also: Formulary
Part A: Hospital coverage. Free for most people who paid Medicare taxes for 10+ years (40 quarters). Covers inpatient hospital stays, skilled nursing facility (limited), home health, hospice.
Part B: Doctor and outpatient coverage. 2026 standard premium: $206.50/month (more for higher-income enrollees, less for MSP recipients). Covers preventive care, doctor visits, durable medical equipment, ambulance.
Part C: Same as Medicare Advantage (MA). The 'C' is the federal designation; nobody actually says 'Part C' in conversation.; See also: MA
Part D: Prescription drug coverage. Either a stand-alone PDP added to Original Medicare or built into an MA-PD plan. 2026 deductible cap: $615; OOP cap: $2,100 (IRA).; See also: Formulary, IRA
QI — Qualifying Individual: Medicare Savings Program tier 3. Pays Part B premium for households 120–135% FPL. Asset-tested. Cannot be combined with full Medicaid.; See also: MSP, QMB, SLMB
QMB — Qualified Medicare Beneficiary: The richest of the three Medicare Savings Programs. Pays Part B premium + Part A/B deductibles and coinsurance. Income ≤ 100% FPL plus an asset test.; See also: MSP, SLMB, QI
SEP — Special Enrollment Period: Trigger-based enrollment window outside the AEP / OEP. Common triggers: losing employer coverage (8 months), moving (2 months), losing Medicaid (3 months for Medicare, 60 days for Marketplace), being dual-eligible (monthly).; See also: AEP, IEP
SHIP — State Health Insurance Assistance Program: Free, federally-funded counseling for Medicare beneficiaries. Wisconsin's SHIP is the Medigap Helpline at 1-800-242-1060. Trained counselors, no commission, won't sell you anything.
SLMB — Specified Low-Income Medicare Beneficiary: Medicare Savings Program tier 2. Pays Part B premium for households 100–120% FPL. Asset-tested.; See also: MSP, QMB, QI
SNP — Special Needs Plan: Medicare Advantage plans for specific populations. Three flavors: D-SNP (dual-eligible), C-SNP (chronic conditions like diabetes/heart failure), I-SNP (institutional / nursing-home).; See also: D-SNP, MA
Spend-down: EBD Medicaid pathway: if you're over the income limit, medical bills (including premiums and copays) reduce your countable income. Once your net is below the threshold, you qualify retroactively.; See also: EBD
SSI — Supplemental Security Income: Federal cash benefit for low-income elderly, blind, or disabled people, run by the Social Security Administration. WI residents on SSI are automatically enrolled in Medicaid SSI.; See also: Medicaid

Don't see a term? Tell us and we'll add it.