Medicare Plan Comparison: Original Medicare vs Advantage vs Medigap

Published 2026-09-10 · Last updated 2026-09-10.

Original Medicare vs Advantage — the fork in the road

Original Medicare means Parts A and B from the federal programme, and most people add a separate drug plan and, often, a Medigap policy. You generally keep broad access to doctors and hospitals that accept Medicare, and your cost-sharing follows the Original Medicare rules plus whatever your Medigap policy covers. The trade-off is that you manage several pieces rather than one plan.

Medicare Advantage, or Part C, replaces Original Medicare with a single private plan that bundles hospital and medical cover and usually includes drug cover. Many plans add extras such as dental, vision or hearing, but they work through a plan network and plan rules, including prior authorisation for some services. Neither path is better in the abstract — the right question is which path fits your doctors, medicines and budget.

The Medigap plus Part D path

On the Original Medicare path, Medigap — also called Medicare Supplement — helps pay some of the cost-sharing that Original Medicare leaves behind, such as deductibles and coinsurance. It does not cover drugs on its own, which is why a standalone Part D plan sits alongside it. Together the three pieces form one coherent route, and the cost calculator page adds their premiums into a single total.

Timing matters for Medigap in a way it does not for other choices, because the open-enrollment window around first eligibility carries protections that later applications may not. Check the enrollment page for the general shape of that window and confirm the current rules on the official source before you delay a Medigap decision.

Side-by-side table — how to read it honestly

The comparison tool on this page asks you to enter two plans' premiums, deductibles and typical copays, then totals them on the same basis. Read the table row by row rather than jumping to the bottom line: premium, drug cost, doctor access, hospital cost-sharing and extras each favour a different path for a different person. A plan that wins on premium can lose on drug cost if your medicines sit on a higher tier.

Also compare what is not in the table: whether your doctors are in network, whether a medicine needs prior authorisation, and whether an extra benefit you value — dental, for example — is actually usable where you live. A benefit you cannot use is not a benefit, however good it looks in a brochure.

Which path fits which need

Choose Original Medicare plus Medigap plus Part D when broad doctor access and predictable cost-sharing matter most to you, and you are comfortable managing separate pieces and paying their combined premiums. Choose Advantage when a single bundled plan, a lower headline premium and included extras matter more, and your doctors and medicines fit comfortably inside that plan's network and formulary.

If you travel often, split time between states, or see specialists in several places, network breadth deserves extra weight. If you rarely use care and your medicines are stable and cheap, premium may deserve more weight. There is no shortcut around listing your own doctors and medicines and checking each plan against that list.

Before you switch

Switching is an annual decision as well as a first-time one, and the windows for changing plans are limited. Before you switch, confirm that your doctors, hospitals and medicines are covered on the new plan, that you understand its prior-authorisation rules, and that you know what happens to any Medigap protection if you leave Original Medicare. Write the answers down; a switch made on premium alone is the most common regret in this whole cluster.

Run both paths through the cost calculator with the same assumptions, then re-read the Parts explained page for any part whose role is still fuzzy. A careful hour here prevents a year of avoidable cost and friction.

ILLUSTRATIVE EXAMPLE

ILLUSTRATIVE EXAMPLE (not a policy fact): Tom, a fictional beneficiary, compares two invented paths in the tool: Path A with three separate monthly amounts he types in, and Path B with a single plan amount plus a drug amount. Path B looks cheaper on premium alone, but once Tom adds his regular medicine amounts — also invented for this example — the gap narrows sharply. He then checks whether his main doctor is in Path B's network before deciding, which is the step the table alone cannot do for him.