Medicare costs are determined by a combination of factors: your work history, your income, the specific parts of Medicare you enroll in, and when you sign up. There’s no single price tag. Most people pay $185 per month for Part B in 2025, but your total cost can be significantly higher or lower depending on your circumstances.
Part A: Work History Sets Your Premium
Part A covers hospital stays, and most people pay nothing for it. If you or your spouse paid Medicare taxes for at least 40 quarters (10 years) during your working life, you qualify for premium-free Part A. Those payroll taxes you paid over the decades are what “bought” this coverage.
If you have fewer than 40 quarters of work history, you’ll pay a monthly premium. People with 30 to 39 quarters pay a reduced rate, while those with fewer than 30 quarters pay the full premium. The exact amounts are recalculated each year by CMS based on program costs. To keep this coverage, you must also enroll in and pay for Part B.
Part B: The Standard Premium and How It’s Set
Part B covers doctor visits, outpatient care, and medical equipment. The standard monthly premium for 2025 is $185.00. CMS recalculates this amount every fall for the following year, based on projected spending for Part B services across the entire Medicare population. By law, premiums collected from beneficiaries must cover roughly 25% of Part B’s total costs, with the federal government funding the remaining 75% through general tax revenue.
This is why the premium changes year to year. When overall healthcare spending rises, or when new expensive treatments enter the market, the Part B premium rises to keep pace. The annual announcement typically comes in October or November for the following January.
How Income Changes What You Pay
Higher-income beneficiaries pay more through a system called the Income-Related Monthly Adjustment Amount, or IRMAA. Medicare uses your tax return from two years prior to determine whether you owe a surcharge. So your 2023 tax return determines your 2025 premiums.
For Part B in 2025, the income thresholds work like this for individual filers:
- $106,000 or less: You pay the standard $185.00
- $106,001 to $133,000: $259.00 per month
- $133,001 to $167,000: $370.00 per month
- $167,001 to $200,000: $480.90 per month
- $200,001 to $499,999: $591.90 per month
- $500,000 or more: $628.90 per month
For joint filers, the thresholds are roughly double: $212,000, $266,000, $334,000, $400,000, and $750,000. Married people who file separately face steeper surcharges at lower income levels, jumping from $185 to $591.90 once income exceeds $106,000.
IRMAA also applies to Part D prescription drug coverage. The surcharges follow the same income brackets, adding $13.70 to $85.80 per month on top of your plan’s base premium. These adjustments are not permanent. If your income drops (due to retirement, divorce, or the death of a spouse), you can appeal to Social Security and request that a more recent tax year be used instead.
Part D: Prescription Drug Premiums
Part D drug coverage is sold by private insurance companies, so premiums vary by plan. Each plan sets its own monthly cost based on the drugs it covers, its pharmacy network, and the insurer’s projected costs for its enrolled population. You’ll typically see premiums ranging from under $10 to over $100 per month depending on the plan.
The national base beneficiary premium, which CMS calculates as a benchmark, is $38.99 in 2026. This figure represents the average cost of standard drug coverage nationwide and serves as the reference point for penalty calculations. Within Part D, you also pay cost-sharing: after meeting your deductible, you typically cover 25% of drug costs as coinsurance until your out-of-pocket spending reaches $2,100 (in 2026). After that, catastrophic coverage kicks in and you pay nothing for covered drugs for the rest of the year.
Late Enrollment Penalties
Signing up late permanently increases what you pay. For Part D, the penalty is 1% of the national base beneficiary premium for every full month you were eligible but didn’t enroll and didn’t have other creditable drug coverage. The gap must be at least 63 days to trigger the penalty. A two-year delay, for example, would add roughly $9.36 per month to your premium for as long as you have Part D coverage.
Part B carries a similar structure: your premium increases 10% for each full 12-month period you could have enrolled but didn’t. Unlike Part D’s penalty, this one is also permanent. These penalties exist to discourage people from waiting until they’re sick to sign up, which would drive costs up for everyone.
The Hold Harmless Rule
If your Part B premiums are deducted from your Social Security check, a provision called “hold harmless” prevents a Part B premium increase from actually reducing your Social Security payment. When Social Security’s cost-of-living adjustment is smaller than the Part B premium increase, your premium is capped so your check doesn’t shrink.
This protection doesn’t apply to everyone. If you’re enrolling in Part B for the first time, if you pay IRMAA surcharges, or if Medicaid pays your premiums, the hold harmless rule doesn’t cover you. For those it does protect, it can mean paying a slightly different Part B premium than the officially announced amount in years when Social Security adjustments are small.
Medicare Advantage: A Different Pricing Model
Medicare Advantage plans (Part C) are offered by private insurers, and their costs are determined through a bidding process. Each year, insurance companies submit bids to CMS by the first Monday in June, estimating what it will cost them to cover the standard Medicare benefits for their enrolled population. CMS compares each bid against a benchmark, which is a per-person spending target set for each geographic area.
If a plan’s bid comes in below the benchmark, the difference (called a rebate) gets returned to enrollees as extra benefits, like dental coverage, vision care, or lower copays. If the bid exceeds the benchmark, the enrollee pays the excess as an additional monthly premium on top of their Part B premium. This is why many Medicare Advantage plans advertise $0 premiums: their bids are low enough relative to the benchmark that no extra charge is needed.
Medigap: Three Pricing Methods
If you stick with Original Medicare and buy a Medigap (supplemental) policy to cover deductibles and coinsurance, the pricing method varies by insurer and state. There are three approaches:
- Community-rated (no-age-rated): Everyone in your area pays the same premium regardless of age. This tends to be the least expensive option over your lifetime.
- Issue-age-rated: Your premium is based on how old you were when you first bought the policy. A 65-year-old pays less than someone who bought the same plan at 70. Premiums still rise with inflation, but not because of your age.
- Attained-age-rated: Premiums start low but increase as you get older. These plans often look like the cheapest option at 65 but become the most expensive over time.
The pricing method matters more than the starting price. An attained-age plan that costs $120 at age 65 could easily cost $300 or more by age 80, while a community-rated plan might start higher but stay more predictable. Not every state offers all three methods, and some states regulate Medigap pricing more tightly than others.