If you’re about to turn 65, the main thing you have to do is enroll in Medicare during a seven-month window built around your birthday, and the penalties for missing it are permanent. That single deadline drives most of what to do when you turn 65, but a few other items belong on the same checklist: stopping Health Savings Account contributions before Medicare starts, understanding that 65 is not full retirement age for Social Security, and claiming the new tax deductions that open up at this age.
Enroll in Medicare Within Your Seven-Month Window
Your Initial Enrollment Period for Medicare runs seven months: the three months before your birthday month, your birthday month itself, and the three months after.1eCFR. 42 CFR 406.21 – Individual Enrollment If you turn 65 in October, the window opens July 1 and closes January 31. Signing up in the three months before your birthday month gets your coverage started the soonest; waiting until the back half of the window delays when benefits begin.
Most people qualify for premium-free Part A (hospital coverage) based on 10 years of Medicare-taxed work, their own or a spouse’s. If you fall short, Part A costs either $311 or $565 per month in 2026 depending on your work quarters. Part B (doctor visits and outpatient care) has a standard 2026 premium of $202.90 regardless of work history.2CMS. 2026 Medicare Parts A and B Premiums and Deductibles
Missing Part B enrollment is where the damage is permanent. Medicare adds 10% to your monthly Part B premium for every full 12 months you could have been enrolled but weren’t, and that surcharge stays on your premium for life.3Medicare. Avoid Late Enrollment Penalties Two years late means 20% extra every month you’re on Medicare, which at 2026 rates is about $40 a month that never goes away. Miss the Initial Enrollment Period entirely and your next chance is the General Enrollment Period, January 1 through March 31, with coverage starting the month after you sign up.4Medicare. When Does Medicare Coverage Start The late penalty still applies on top of that gap.
Check Whether You’ll Be Enrolled Automatically
Whether you have to do anything depends on whether you’re already collecting Social Security. If you started Social Security before 65, you’ll be automatically enrolled in Part A when you turn 65, and your Medicare card usually arrives in the mail about three months before your birthday.5Social Security Administration. When to Sign Up for Medicare You’ll be enrolled in Part B too unless you actively decline it.
If you haven’t started Social Security, nothing happens on its own. You have to apply for Medicare yourself through the Social Security Administration’s website or a local field office during your seven-month window. This is where most people miss the deadline, because there’s no automatic backstop. Put it on your calendar independently.
If You’re Still Working at 65
Being covered by a group health plan through your job at 65 changes the calculation, and the size of your employer decides the answer.
At an employer with 20 or more employees, the group plan pays first and Medicare pays second.6Office of the Law Revision Counsel. 42 USC 1395y – Exclusions From Coverage and Medicare as Secondary Payer You can delay Part B without any late penalty as long as that employer coverage stays active and is based on current employment.7Medicare. Who Pays First When you leave the job or lose the coverage, a Special Enrollment Period gives you eight months to sign up for Part B penalty-free.8CMS. Application for Enrollment in Medicare Part B – Medical Insurance
One detail catches people badly: COBRA and retiree health plans do not count as coverage based on current employment. If you leave your job and go on COBRA, the eight-month clock started running when your employment ended, not when COBRA runs out. Sign up for Part B a month or two before your job ends to avoid a gap.
At an employer with fewer than 20 employees, the rules flip. Medicare becomes the primary payer and the employer plan only picks up what Medicare doesn’t.7Medicare. Who Pays First You should enroll in Part B during your Initial Enrollment Period even though you have job coverage. Skip it and the employer plan may not cover the full cost of your care.
Decide on Medigap and Drug Coverage on the Same Clock
Once you have Part A and Part B, two other decisions run on their own deadlines.
Your Medigap Open Enrollment Period is a six-month window that starts the first day of the month you’re both 65 or older and enrolled in Part B.9Medicare. When Can I Buy a Medigap Policy During those six months, insurers have to sell you any Medigap policy they offer at the standard price regardless of your health. After the window closes, insurers in most states can use medical underwriting, meaning a pre-existing condition could make a policy far more expensive or unavailable. If you want Medigap, this is the one window where the playing field is level.
Part D (prescription drugs) requires its own enrollment, either as a standalone plan or bundled inside a Medicare Advantage plan. Skipping it when you’re first eligible triggers a permanent penalty: 1% of the national base beneficiary premium ($38.99 in 2026) multiplied by the number of full months you went without creditable drug coverage.10CMS. 2026 Medicare Part D Bid Information and Part D Premium Stabilization Demonstration Parameters Twenty-four uncovered months adds roughly $9.36 a month to your Part D premium permanently. The exception is drug coverage through an employer or union that’s at least as comprehensive as a standard Part D plan.
Stop HSA Contributions Before Medicare Starts
If you’ve been putting money into a Health Savings Account through a high-deductible health plan, Medicare ends that. Your HSA contribution limit drops to zero the first month you’re entitled to Medicare benefits.11Office of the Law Revision Counsel. 26 USC 223 – Health Savings Accounts For reference, the 2026 annual limits are $4,400 for self-only coverage, $8,750 for family coverage, plus a $1,000 catch-up if you’re 55 or older.12Internal Revenue Service. IRS Notice 2026-05 – HSA Contribution Limits
The trap is the six-month lookback. When you apply for Medicare Part A after age 65, coverage is retroactive up to six months (though never before your 65th birthday). Any HSA contributions made during those retroactive months become excess contributions, and the IRS applies a 6% excise tax each year they stay in the account.13Internal Revenue Service. Publication 969 – Health Savings Accounts and Other Tax-Favored Health Plans Applying for Social Security causes the same problem because it triggers automatic Part A enrollment. Stop HSA contributions at least six months before you plan to enroll in Medicare or claim Social Security.
Money already in the HSA stays put. You can still use it tax-free for qualified medical expenses at any age, including Medicare premiums, copays, and deductibles. After 65, you can also pull HSA money out for non-medical expenses without the 20% penalty, though you’ll pay regular income tax on the withdrawal.11Office of the Law Revision Counsel. 26 USC 223 – Health Savings Accounts To pro-rate your final year’s contribution, divide the annual limit by 12 and multiply by the number of months you were eligible before Medicare started.
Don’t Assume 65 Is Full Retirement Age for Social Security
Turning 65 and reaching full retirement age for Social Security are not the same thing. If you were born in 1961, your full retirement age is 67.14Social Security Administration. Benefits Planner – Retirement – Born in 1960 or Later Claim Social Security at 65 and you’ll take a permanent reduction compared to waiting.
If you claim at 65 while still working, the earnings test kicks in. In 2026, Social Security withholds $1 in benefits for every $2 you earn above $24,480.15Social Security Administration. Receiving Benefits While Working In the calendar year you reach full retirement age, the threshold rises to $65,160 and the reduction drops to $1 for every $3 above the limit. The withheld amounts aren’t gone forever; Social Security recalculates your monthly payment upward once you hit full retirement age. But in the near term the check is smaller than people expect.
Spousal benefits shrink too. The maximum spousal benefit is 50% of the working spouse’s primary insurance amount, but only at full retirement age. Claiming at 65 drops the spousal benefit to roughly 37.5% of the worker’s amount.16Social Security Administration. Benefits for Spouses
Claim the Tax Deductions That Open Up at 65
Your 65th birthday adds to your standard deduction. Taxpayers 65 and older get an additional standard deduction on top of the regular one: $2,050 for single filers in 2026, and $1,650 per qualifying spouse for married couples filing jointly.
For tax years 2025 through 2028, a new provision adds another $6,000 deduction per eligible taxpayer age 65 or older, on top of the additional standard deduction. Two qualifying spouses get $12,000 combined. It’s available whether you take the standard deduction or itemize. The deduction phases out at 6% of modified adjusted gross income above $75,000 for single filers and $150,000 for married filing jointly.17Internal Revenue Service. One, Big, Beautiful Bill Act – Tax Deductions for Working Americans and Seniors
Depending on income, you may also qualify for the Credit for the Elderly or the Disabled, worth between $3,750 and $7,500 depending on filing status. It’s claimed on Schedule R of Form 1040 and has income limits that exclude higher earners.18Internal Revenue Service. Credit for the Elderly or the Disabled Tax software usually flags it, but it’s one of the more commonly overlooked credits if you file by hand.