The 2026 Medigap Buying Guide: A Complete Walkthrough From Eligibility to Enrollment

Buying a Medigap policy is a once-per-lifetime decision made in a six-month window, and most people make it with a sales call instead of a framework. This guide walks the whole path: when you qualify, how the letters work, how carriers price the same benefit differently, and the sequencing that protects your switching rights for the next decade.

Step 1: Know your six-month window

Your Medigap Open Enrollment Period starts the month you turn 65 and enroll in Medicare Part B — it runs six months, and during it every carrier must sell you any plan it offers at your age-bracket price with no health questions. Outside that window, in most states, carriers run medical underwriting: the quote on the website is conditional until you pass. People who miss the window pay for it for years, so calendar it the day you enroll in Part B.

Step 2: Choose the letter before the carrier

Benefits are federally standardized — a Plan G pays identically from every carrier. That collapses the decision into two questions: which letter, and which book of business. For new eligibles the shortlist is G (full coverage after the $257 Part B deductible), N (same coverage with $20/$50 copays, priced 15–30% lower), and HD-G ($2,870 deductible, 40–60% cheaper). K and L serve capped-budget profiles. Everything else is niche.

Step 3: Price the book, not the quote

The same letter varies 30–60% across carriers in one ZIP — and entry quotes are a terrible predictor of five-year cost. Attained-age books reprice annually as you age; issue-age books hold the age-65 rate and drift only with overall increases; community-rated books pool everyone. Ask each carrier for its five-year increase history on the specific plan — this single number separates disciplined books from teaser-rate traps better than any marketing claim.

Step 4: Understand what Medigap does not cover

No letter covers dental, routine vision, hearing aids, or prescriptions (that is Part D’s job). Six letters — C, D, F, G, M, N — add foreign travel emergency at 80% after $250, capped at $50,000 lifetime. If prescriptions matter, budget a Part D plan separately and re-shop it every fall; the two purchases are independent.

Step 5: Enroll deliberately, then document everything

Apply in month one of your OEP, not month six — approvals are instant and coverage starts cleanly. Save your application, approval, and the carrier’s creditable-coverage notices. And record your health status at purchase: it defines whether you could pass underwriting later, which determines how much weight the premium really deserves. In states with a birthday rule or annual guaranteed-issue rights (California, New York, Washington and others), the calculus loosens; everywhere else, year one is the semi-permanent choice.

Continue reading: the full plan comparison matrix, the Plan G age curve, and the six-month OEP explained.