# When is my Medicare eligibility?

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.

- Page: https://www.acalculator.org/finance/medicare-eligibility-calculator
- JSON spec: https://www.acalculator.org/finance/medicare-eligibility-calculator.json
- Version: fe90cfa80b59

## Default answer

Example with the default inputs (Date of birth November 20, 1961, Date you sign up (optional) September 10, 2026): 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.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| birth | Date of birth | Your date of birth, which sets the month you reach 65. |
| signup | Date you sign up (optional) | The date you apply for Part B, to see when your coverage starts. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| start | Earliest coverage start | 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. |
| turn65 | You turn 65 on | Your 65th birthday (February 29 birthdays fall on February 28). |
| iepStart | Initial Enrollment Period opens | The first day of the third month before the month you attain 65. |
| iepEnd | Initial Enrollment Period closes | The last day of the third month after the month you attain 65. |
| signBy | Sign up by | The last day to sign up and still start coverage on the earliest date. |
| coverage | Coverage starts | When Part B starts for the date you sign up. |
| period | Your sign-up falls in | The enrollment period of the date you sign up. |
| penalty | Part B late penalty | Extra Part B premium for signing up after the Initial Enrollment Period: 10% for each full 12 months. |

## 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.

## Worked examples

1. birth = 1961-11-20, signup = 2026-09-10 gives 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.
2. birth = 1961-07-01, signup = 2026-07-15 gives 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.
3. birth = 1960-02-29 gives 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.
4. birth = 1960-05-20, signup = 2027-02-10 gives 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.

## FAQ

### When am I eligible for Medicare?

Most people become eligible for Medicare in the month they turn 65. Medicare counts you as 65 on the day before your 65th birthday, so if you were born on the 1st of a month, you are eligible from the month before. People under 65 can qualify through disability benefits, ALS or end-stage renal disease.

### What is the Initial Enrollment Period?

It is the 7 months around the month you turn 65: the 3 months before, that month, and the 3 months after (42 CFR 406.21 and 407.14). Turning 65 on November 20, 2026, your Initial Enrollment Period runs from August 1, 2026 to February 28, 2027.

### When does coverage start if I sign up during the Initial Enrollment Period?

Sign up in the 3 months before the month you turn 65 and coverage starts on the first day of that month. Sign up in that month or the 3 months after it and coverage starts on the first day of the month after you sign up (42 CFR 407.25, for sign-ups from 2023).

### What if I miss my Initial Enrollment Period?

You can sign up in the General Enrollment Period, January 1 to March 31 each year, and coverage starts the month after you sign up. Unless you had a Special Enrollment Period, your Part B premium goes up 10% for each full 12 months you could have had Part B but did not, for as long as you have Part B.

### How is the Part B late penalty counted?

The months run from the end of your Initial Enrollment Period to the end of the month you sign up, and each full 12 months adds 10% (42 CFR 408.22 and 408.24(b)). If your Initial Enrollment Period ended on August 31, 2025 and you sign up in February 2027, that is 18 months: 1 full year, so 10%.

### Am I enrolled automatically?

Yes, if you start getting Social Security benefits at least 4 months before you turn 65: you get Part A and Part B automatically, and your Medicare card arrives about 3 months before coverage starts, which is the first day of the month you turn 65. Otherwise you sign up with Social Security.

### Do I have to sign up for Part B at 65 if I still work?

Not if you or your spouse have health coverage through a current job. You can then sign up any time while you work there, or within 8 months after the job or the coverage ends, whichever comes first, with no penalty (COBRA does not extend it). This calculator does not cover Special Enrollment Periods.

## 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)