3 Things a 65-Year-Old Should Do Before Medicare Open Enrollment Opens Oct. 15

You turned 65 this year and chose a Medicare plan in a rush. Open enrollment is your first chance to change that choice for 2027, and what you pick this fall determines your costs for a decade. The weeks before the window opens are the calm stretch. Here are three things to do with them.

Step 1: Pull Your 2025 Tax Return Before Any Plan Pitch Lands

Medicare sets its income surcharge, IRMAA, from your tax return two years back. That means 2025 income drives 2027 premiums. The income that counts is modified adjusted gross income (MAGI): adjusted gross income together with tax-exempt interest, including municipal bonds you never paid tax on.

Most readers are safe. CMS says the surcharge affects roughly 8% of people with Medicare Part B. If your MAGI falls well under the initial threshold in this table, it doesn’t apply to you.

A 65-year-old faces a specific problem. Your 2025 return probably shows a full salary. If you have retired since then, Social Security’s Form SSA-44 lets you request a new calculation based on work stoppage or reduction. The form only covers life-changing events; a Roth conversion or home sale that raised income will not qualify. People who skip this check first see the surcharge on a bill. Your MAGI also tells you whether a Roth conversion before year-end would push 2026 income, which sets 2028 premiums, over a line.

Part B premiums are taken directly from your monthly benefit checks. The 2027 COLA is tracking toward 3.5% to 3.6%, and the new Part B premium will take part of that raise. Several surcharges and coverage gaps quietly raise the real cost of Medicare well above the sticker premium, and IRMAA is among them (we laid out the rest in a free guide here: Medicare’s Hidden Bills).

Step 2: Build a Full Prescription List to Price Against Formularies

Write down every drug, its dose, and how often you fill it. Part D and Advantage formularies change yearly. A plan covering your drug in 2026 can move it to a pricier tier or drop it in 2027. Enter the complete list into Medicare’s Plan Finder for every plan you’re considering. People who wait tend to pick on premium, then find at the pharmacy that their zero-premium plan charges full price for the one brand-name drug they rely on.

Step 3: Confirm Your Doctors Are in Each Network You’re Weighing

Call your doctors’ billing offices directly and ask whether they will be in network for each specific plan in 2027. Insurer directories run behind. Advantage plans require you to stay in-network and often require prior authorization for specialists and procedures. Original Medicare works with any doctor nationwide who takes Medicare. People who wait often find the network gap after a diagnosis, the worst time to switch.

Why Your First Coverage Choice Is Hard to Undo

With Original Medicare plus Medigap Plan G, you pay a supplement premium and the 2026 Part B deductible of $283. Plan G covers the Part A hospital deductible of $1,736 per benefit period and skilled nursing coinsurance of $217.00 a day for days 21 through 100. Advantage plans charge low or zero premiums but come with network rules and an in-network out-of-pocket cap that excludes drug spending and out-of-network care.

Federal law ensures you can buy Medigap only during a one-time, six-month window starting when you turn 65 and enroll in Part B. After it closes, insurance companies in most states can review your health and deny coverage or charge more. A few states, including New York and Connecticut, offer broader protection. If you joined an Advantage plan at 65, a trial right lets you return to Original Medicare with ensures Medigap access within your first 12 months.

If you have chronic conditions or see specialists often, lock in Original Medicare plus Plan G while ensures issue still protects you. A healthy 65-year-old who picks Advantage based on premium alone gives up future flexibility for savings today.

Which Step Most 65-Year-Olds Skip

Most people skip the income check. Drug lists and doctor calls feel like shopping; pulling a tax return feels like homework. But the income check is the only step that can add surcharges to both Part B and Part D for a full year, and the only one with a form to fight it. Pull your 2025 return this weekend and find your MAGI. If you’ve retired, have your retirement letter ready for SSA-44.

Rules used: plan year 2026. All premium, deductible and surcharge figures come from the CMS fact sheet 2026 Medicare Parts A & B Premiums and Deductibles, released Nov. 14, 2025. They are the current reference point until CMS publishes 2027 amounts.

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