Medicare Navigator

Medicare is the most consequential financial decision most retirees will ever make. It governs healthcare for the rest of your life, runs $5K-$15K per year per person, and most decisions are permanent or hard to reverse. Yet most people approach it with a vague plan and a TV commercial.

The first decision: Original Medicare + Medigap, or Medicare Advantage? Original Medicare (Parts A and B) is the federal program — it covers most things but has no out-of-pocket maximum. A 20% coinsurance on a $200K cancer treatment is $40K out of your pocket. Medigap fills that gap for an extra $150-300/month, with no network restrictions and full coverage anywhere that takes Medicare. Medicare Advantage (Part C) is a private bundled plan that replaces Parts A, B, and usually D — lower or zero premium, but with provider networks, prior authorization, and an out-of-pocket max around $5K-$8.5K per year. The choice usually comes down to: do you value flexibility (Original + Medigap) or low monthly cost (Advantage)?

The IRMAA trap. If your MAGI exceeds the threshold ($109K single / $218K married for 2026), you pay an Income-Related Monthly Adjustment Amount surcharge on both Part B and Part D — up to $446/month per person at the top tier, both spouses get hit. And IRMAA uses your MAGI from two years ago, so a 2026 Roth conversion shows up in 2028 premiums. The good news: it's a cliff, not a slope. Stop $1 short of the threshold and you pay nothing extra. This tool shows your current bracket and the distance to the next one.

The late-enrollment trap. If you're not on creditable employer coverage and you delay Medicare enrollment past 65, you pay a permanent penalty: Part B adds 10% per year delayed, Part D adds 1% per month. These are lifetime surcharges — pay them every month for the rest of your life. The exception: if you have employer coverage from a 20+ employee company, you can defer penalty-free until you stop working. Smaller employers, COBRA, retiree health plans, ACA marketplace — none of these qualify. Get it wrong and you're paying for decades.

The Medigap underwriting trap. When you first enroll in Part B, you have a 6-month guaranteed-issue window to buy any Medigap plan without medical underwriting. After that window closes, switching plans requires medical underwriting in most states — and pre- existing conditions can mean denial. The practical implication: if you start with Medicare Advantage and later decide you want Medigap, you may not be allowed to switch. Pick carefully the first time.

None of this is in your retirement calculator's “life expectancy / withdrawal rate” box. But it consumes 5-10% of your retirement budget every year, and the wrong path can cost six figures over a 25-year retirement. This tool is the first step toward making the decision deliberately.