{
  "id": "medicare-eligibility",
  "version": "fe90cfa80b59",
  "status": "published",
  "name": "Medicare Eligibility Calculator",
  "question": "When is my Medicare eligibility?",
  "summary": "Works out when you can get Medicare at 65 from your date of birth: your 7-month Initial Enrollment Period, the earliest coverage date, and when Part B starts for the date you sign up.",
  "category": "finance",
  "subcategory": "retirement",
  "url": "https://www.acalculator.org/finance/medicare-eligibility-calculator",
  "markdown": "https://www.acalculator.org/finance/medicare-eligibility-calculator.md",
  "kind": "function",
  "method": "You attain 65 the day before your 65th birthday. Initial Enrollment Period = the first day of the 3rd month before that month to the last day of the 3rd month after it. Sign up in its first 3 months: coverage starts the first day of the month you attain 65; in its last 4 months: the first day of the month after you sign up. General Enrollment Period (January 1 to March 31): the month after you sign up, plus 10% Part B penalty for each full 12 months after the Initial Enrollment Period.",
  "assumptions": [
    "Medicare at age 65, not Medicare through disability benefits, ALS or end-stage renal disease.",
    "If you start Social Security benefits at least 4 months before you turn 65, you get Parts A and B automatically from the first day of the month you attain 65.",
    "Coverage dates are for Part B (and Part A you buy); premium-free Part A has its own start rules. Special Enrollment Periods (for example after job-based coverage ends) are not covered.",
    "Birth dates from 1900 to 2100, sign-up dates to 2200."
  ],
  "inputs": {
    "$schema": "https://json-schema.org/draft/2020-12/schema",
    "type": "object",
    "properties": {
      "birth": {
        "title": "Date of birth",
        "description": "Your date of birth, which sets the month you reach 65.",
        "type": "string",
        "format": "date"
      },
      "signup": {
        "title": "Date you sign up (optional)",
        "description": "The date you apply for Part B, to see when your coverage starts.",
        "type": "string",
        "format": "date"
      }
    }
  },
  "outputs": {
    "start": {
      "label": "Earliest coverage start",
      "description": "The first day of the month you attain 65: Medicare starts then if you sign up in the first 3 months of your Initial Enrollment Period.",
      "format": "date"
    },
    "turn65": {
      "label": "You turn 65 on",
      "description": "Your 65th birthday (February 29 birthdays fall on February 28).",
      "format": "date"
    },
    "iepStart": {
      "label": "Initial Enrollment Period opens",
      "description": "The first day of the third month before the month you attain 65.",
      "format": "date"
    },
    "iepEnd": {
      "label": "Initial Enrollment Period closes",
      "description": "The last day of the third month after the month you attain 65.",
      "format": "date"
    },
    "signBy": {
      "label": "Sign up by",
      "description": "The last day to sign up and still start coverage on the earliest date.",
      "format": "date"
    },
    "coverage": {
      "label": "Coverage starts",
      "description": "When Part B starts for the date you sign up.",
      "format": "date"
    },
    "period": {
      "label": "Your sign-up falls in",
      "description": "The enrollment period of the date you sign up.",
      "format": "text"
    },
    "penalty": {
      "label": "Part B late penalty",
      "description": "Extra Part B premium for signing up after the Initial Enrollment Period: 10% for each full 12 months.",
      "format": "percent"
    }
  },
  "defaultAnswer": {
    "inputs": {
      "birth": "1961-11-20",
      "signup": "2026-09-10"
    },
    "outputs": {
      "start": "2026-11-01",
      "turn65": "2026-11-20",
      "iepStart": "2026-08-01",
      "iepEnd": "2027-02-28",
      "signBy": "2026-10-31",
      "coverage": "2026-11-01",
      "period": "Initial Enrollment Period, before the month you turn 65"
    },
    "text": "Born on November 20, 1961, you turn 65 on November 20, 2026; your Initial Enrollment Period runs from August 1, 2026 to February 28, 2027, and Medicare can start on November 1, 2026."
  },
  "examples": [
    {
      "given": {
        "birth": "1961-11-20",
        "signup": "2026-09-10"
      },
      "expect": {
        "turn65": "2026-11-20",
        "start": "2026-11-01",
        "iepStart": "2026-08-01",
        "iepEnd": "2027-02-28",
        "signBy": "2026-10-31",
        "coverage": "2026-11-01"
      },
      "source": "42 CFR 406.21 (7-month Initial Enrollment Period; General Enrollment Period January 1 to March 31) and 407.25(a)(2) (coverage start for enrollments on or after January 1, 2023), https://www.law.cornell.edu/cfr/text/42/407.25; Medicare.gov, When does Medicare coverage start? (Initial Enrollment Period; a birthday on the 1st starts coverage the month before), https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-does-medicare-coverage-start; hand calculation in content.mdx; Python 3 check in docs/progress/WP-142/xcheck.py"
    },
    {
      "given": {
        "birth": "1961-07-01",
        "signup": "2026-07-15"
      },
      "expect": {
        "turn65": "2026-07-01",
        "start": "2026-06-01",
        "iepStart": "2026-03-01",
        "iepEnd": "2026-09-30",
        "coverage": "2026-08-01"
      },
      "source": "Medicare.gov, When does Medicare coverage start? (Initial Enrollment Period; a birthday on the 1st starts coverage the month before), https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-does-medicare-coverage-start (a birthday on the first of the month); 20 CFR 404.2(c)(4): an individual attains an age on the day before the anniversary of birth, https://www.law.cornell.edu/cfr/text/20/404.2; 42 CFR 406.21 (7-month Initial Enrollment Period; General Enrollment Period January 1 to March 31) and 407.25(a)(2) (coverage start for enrollments on or after January 1, 2023), https://www.law.cornell.edu/cfr/text/42/407.25; Python 3 check in docs/progress/WP-142/xcheck.py"
    },
    {
      "given": {
        "birth": "1960-02-29"
      },
      "expect": {
        "turn65": "2025-02-28",
        "start": "2025-02-01",
        "iepStart": "2024-11-01",
        "iepEnd": "2025-05-31"
      },
      "source": "42 CFR 406.21 (7-month Initial Enrollment Period; General Enrollment Period January 1 to March 31) and 407.25(a)(2) (coverage start for enrollments on or after January 1, 2023), https://www.law.cornell.edu/cfr/text/42/407.25; 20 CFR 404.2(c)(4): an individual attains an age on the day before the anniversary of birth, https://www.law.cornell.edu/cfr/text/20/404.2; Python 3 check in docs/progress/WP-142/xcheck.py"
    },
    {
      "given": {
        "birth": "1960-05-20",
        "signup": "2027-02-10"
      },
      "expect": {
        "iepEnd": "2025-08-31",
        "coverage": "2027-03-01",
        "penalty": 10
      },
      "source": "42 CFR 406.21 (7-month Initial Enrollment Period; General Enrollment Period January 1 to March 31) and 407.25(a)(2) (coverage start for enrollments on or after January 1, 2023), https://www.law.cornell.edu/cfr/text/42/407.25 (406.21(c): coverage the month after you sign up); 42 CFR 408.22 and 408.24(b) (10% for each full 12 months from the close of the Initial Enrollment Period to the close of the month you enroll), https://www.law.cornell.edu/cfr/text/42/408.24; Medicare.gov, Avoid late enrollment penalties, https://www.medicare.gov/basics/costs/medicare-costs/avoid-penalties; hand calculation in content.mdx; Python 3 check in docs/progress/WP-142/xcheck.py"
    }
  ],
  "sources": [
    "Medicare.gov, When does Medicare coverage start?: the 7-month Initial Enrollment Period; coverage starts the month you turn 65 if you sign up before it, and the next month if you sign up in it or the 3 months after; if your birthday is on the first of the month, coverage starts the month before you turn 65; the General Enrollment Period, January 1 to March 31. https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-does-medicare-coverage-start (retrieved 2026-10-19)",
    "42 CFR 406.21 (initial enrollment period: 7 months from the third month before the month the individual first meets the requirements; general enrollment period January 1 to March 31, entitlement from the month after enrollment from 2023), Legal Information Institute. https://www.law.cornell.edu/cfr/text/42/406.21 (retrieved 2026-10-19)",
    "42 CFR 407.25 (coverage period for enrollment in the initial enrollment period: on or after January 1, 2023, enrollment in the first 3 months starts entitlement with the first month of eligibility; in the last 4 months, with the month after enrollment), Legal Information Institute. https://www.law.cornell.edu/cfr/text/42/407.25 (retrieved 2026-10-19)",
    "Medicare.gov, How do I sign up for Medicare? (automatic Part A and Part B when you start Social Security benefits at least 4 months before you turn 65; the card comes 3 months before coverage starts) and When can I sign up for Medicare? (job-based coverage: up to 8 months after the job or the coverage ends). https://www.medicare.gov/basics/get-started-with-medicare/sign-up/how-do-i-sign-up-for-medicare and https://www.medicare.gov/basics/get-started-with-medicare/sign-up/when-can-i-sign-up-for-medicare (retrieved 2026-10-19)",
    "20 CFR 404.2(c)(4): an individual attains a given age on the first moment of the day before the anniversary of birth. https://www.law.cornell.edu/cfr/text/20/404.2 (retrieved 2026-10-19)",
    "42 CFR 408.22 and 408.24(b) (10% for each full 12 months; for enrollments from 2023, the months from the close of the initial enrollment period to the close of the month of enrollment), Legal Information Institute. https://www.law.cornell.edu/cfr/text/42/408.24 (retrieved 2026-10-19); Medicare.gov, Avoid late enrollment penalties. https://www.medicare.gov/basics/costs/medicare-costs/avoid-penalties (retrieved 2026-10-19)"
  ],
  "related": [
    "part-d-penalty",
    "social-security",
    "retirement-age",
    "retirement"
  ],
  "changelog": []
}