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Medicare Advantage and lab tests

More than half of people on Medicare are in a Medicare Advantage plan. Everything this site says about coverage still applies to you. Three things can be different, and one of them is money.

What stays the same

Federal regulation (42 CFR 422.101) requires a Medicare Advantage organization to provide coverage of "all services that are covered by Part A and Part B of Medicare." Medicare.gov puts it in one sentence: plans "must cover all medically necessary services that Original Medicare covers." So the national coverage rules on this site, the ones that say which diagnoses support a vitamin D test or a ferritin test, are a floor for every plan. A plan can be more generous. It cannot be less.

The same is true of preventive screenings. Medicare.gov's Part B page says a Medicare Advantage plan "may have different rules," but "must give you at least the same coverage as Original Medicare."

What can differ

Medicare.gov's comparison of Original Medicare and Medicare Advantage lists the differences plainly. In a Medicare Advantage plan:

• Network. "You may need to use doctors and other providers who are in the plan's network and service area." For lab work, that means the plan may name which lab company you use. A draw at the wrong lab can be billed to you in full.
• Prior authorization. "You may need to get approval (prior authorization) from your plan before it covers certain services." Original Medicare, by contrast, needs no approval in most cases. KFF reports that nearly all Medicare Advantage enrollees (99 percent) are in plans that require prior authorization for some services; which services varies by plan.
• Referrals. "You may need to get a referral to see a specialist."
• Cost. "Plans may have different out-of-pocket costs for certain services." Medicare's own booklet says it directly: "The plan (rather than Medicare) decides how much you pay for the covered drugs, items, and services you get."

In exchange, every Medicare Advantage plan has a yearly limit on what you pay out of pocket for Part A and Part B services, which Original Medicare does not have. For 2026 that limit cannot exceed $9,250 for in-network care; the average plan sets it around $5,400 (KFF).

Where the lab copay is written down

Every plan sends an Evidence of Coverage each fall (Medicare says by October 15). Its medical benefits chart lists what the plan covers and what you pay, service by service. Look for the row called something like "Outpatient diagnostic tests and therapeutic services and supplies" and, under it, "Laboratory tests." One 2026 plan we read lists "$0 copayment for Medicare-covered lab services" there, next to $30 for X-rays and $45 for other diagnostic tests. Your plan's row may say $0, or it may say a number. That row, not this site, is the answer for your plan.

The same document says which services need prior authorization and what happens if you go out of network. If you never received it, Medicare.gov says to contact your plan.

What to ask your plan before the draw

This is ClaraCover's checklist, put together from the rules above. It takes one phone call to the number on your card.

1. "Is this lab in my network?" Give them the lab company and location on your order.
2. "Does this test need prior authorization?" If yes, it is your doctor's office that has to request it, so ask them to.
3. "What is my copay for lab tests?" Ask them to read the Evidence of Coverage row to you.
4. If in doubt, ask for an "organization determination." Medicare's booklet describes this as a decision you can request that "tells you whether a service, item, or drug will be covered, or how much you'll have to pay," before you get it.

Then the rest of this site works the same way for you. The test pages tell you whether Medicare's policy covers the test for your diagnosis, which is the floor your plan must meet, and what the test costs to buy directly if it turns out not to be covered.

Which plans are these?

In 2026, 55 percent of eligible beneficiaries, about 35 million people, are in Medicare Advantage (KFF). UnitedHealthcare has about 26 percent of that enrollment and Humana about 20 percent, so nearly half of all Medicare Advantage members are in one of those two. Each carrier sells hundreds of plan variants that differ by county, which is why this page cannot tell you your copay and your Evidence of Coverage can.

Sources

• 42 CFR 422.101, Requirements relating to basic benefits (Cornell LII copy of the regulation)
• Medicare.gov: Compare Original Medicare & Medicare Advantage
• Medicare.gov: Understanding Medicare Advantage Plans (booklet 12026)
• Medicare.gov: What Part B covers
• Medicare.gov: Diagnostic laboratory tests
• Medicare.gov: Evidence of Coverage
• Medicare.gov: How to get Medicare services
• KFF: Medicare Advantage in 2026, Enrollment Update and Key Trends
• KFF: Medicare Advantage in 2026, Premiums, Out-of-Pocket Limits, Supplemental Benefits, and Prior Authorization
• Example Evidence of Coverage: Peoples Health Medicare Advantage Giveback LA-4 (HMO-POS), 2026, Chapter 4 medical benefits chart

Checked September 27, 2026. This page explains published Medicare rules. It is not insurance, financial, or medical advice, does not recommend any plan, and cannot tell you your plan's copay; your Evidence of Coverage can. ClaraCover has no relationship with any Medicare Advantage plan.