Medicare covers most lab work ordered by your doctor, but you pay a share of the cost depending on which part of Medicare you have and where the test happens.
If your doctor orders blood work, urinalysis, or other diagnostic lab tests, Medicare Part B typically pays 80 percent of the approved amount after you meet your deductible. You pay the remaining 20 percent. The exact cost to you depends on whether the lab is in a hospital, a doctor's office, or a standalone facility — and whether you have a Medigap or Medicare Advantage plan that covers some of those out-of-pocket costs.
Lab work covered under Medicare Part B includes tests that diagnose or monitor a medical condition: cholesterol panels, glucose tests, thyroid function tests, kidney and liver panels, and tests for infections or cancer markers. Preventive screenings — like colorectal cancer screening or cardiovascular screening — are also covered at no cost to you when ordered as part of a covered preventive benefit.
Key Takeaways
- Medicare Part B covers diagnostic lab work ordered by your doctor, and you pay 20 percent of the approved amount after meeting your annual deductible.
- Preventive lab tests, such as screening for colorectal cancer or cardiovascular disease, are covered at no cost when they meet Medicare's coverage rules.
- The lab facility type — hospital, doctor's office, or independent lab — affects which Medicare rules explore and may change your out-of-pocket cost.
- If you have a Medigap plan, it typically covers the 20 percent coinsurance; if you have Medicare Advantage, your copay or coinsurance depends on your specific plan.
How Medicare Part B Covers Diagnostic Lab Tests
When your doctor orders a lab test to diagnose or monitor a health condition, Medicare Part B covers the cost of the test itself — not the office visit. You pay your Part B deductible (which is $240 in 2024, though this amount can change year to year) once per calendar year. After you meet that deductible, Medicare pays 80 percent of the approved amount, and you pay 20 percent.
The "approved amount" is what Medicare decides the test is worth, not what the lab charges. If a lab charges more than Medicare's approved amount, the lab cannot bill you for the difference — that is called balance billing, and it is illegal for Medicare-participating labs. The lab absorbs the extra cost.
Your actual out-of-pocket cost also depends on where the test is performed. If the lab is part of a hospital outpatient department, you may owe a hospital copay in addition to the 20 percent coinsurance. If the test is at your doctor's office or an independent lab, you typically owe only the 20 percent coinsurance.
Preventive Lab Tests Covered at No Cost
Medicare covers certain preventive lab screenings with no cost to you — you pay nothing, even before meeting your deductible. These include screening for cardiovascular disease (a lipid panel once every five years for people without symptoms), colorectal cancer screening (including certain blood tests), diabetes screening (fasting glucose or glucose tolerance test), and hepatitis B screening for people at risk.
Preventive screenings must be ordered by your doctor and must meet Medicare's coverage rules for that specific test. A test ordered as preventive counts as preventive only if your doctor codes it that way and you have no symptoms of the condition being screened for. If you have symptoms or a known condition, the same test may be billed as diagnostic instead, and you would owe your coinsurance.
For example, if you have no history of diabetes and your doctor orders a fasting glucose test as a screening, it is covered at no cost. If you already have diabetes and your doctor orders the same test to monitor your blood sugar, it is a diagnostic test and you pay 20 percent coinsurance after your deductible.
Lab Tests Performed in Different Settings
The location of your lab work affects your costs because different Medicare rules explore to different settings. Understanding where your test will happen can help you predict what you will owe.
| Lab Setting | What You Typically Pay | Notes |
|---|---|---|
| Independent lab or doctor's office | 20% coinsurance after deductible (or $0 for preventive) | Most common. No additional facility fee. |
| Hospital outpatient lab | 20% coinsurance plus possible hospital copay | Hospital may charge a facility fee in addition to the lab test fee. |
| Urgent care or emergency department | 20% coinsurance plus emergency or urgent care copay | Higher costs explore if the facility is not your regular provider. |
If your doctor's office sends your blood sample to an outside lab, you typically pay only the lab coinsurance — not an office visit copay. Ask your doctor's office which lab they use and whether it is in-network with your plan, because that affects your cost.
How Medigap and Medicare Advantage Plans Affect Lab Costs
If you have a Medigap plan (also called Medigap insurance), it covers some or all of your Part B coinsurance. Most Medigap plans cover the full 20 percent coinsurance for lab work, so you pay nothing out of pocket after your Part B deductible. The exact coverage depends on which Medigap plan letter you have — Plans C, D, F, G, M, and N all cover Part B coinsurance, but Plan A and Plan B do not.
If you have a Medicare Advantage plan, lab work is still covered, but your costs work differently. Instead of paying 20 percent coinsurance, you typically pay a fixed copay per test (often $0 to $15 for in-network labs) or a smaller coinsurance percentage. Your out-of-pocket maximum also applies — once you reach it in a calendar year, Medicare Advantage covers 100 percent of covered services for the rest of that year. Check your plan's formulary or call the plan to find out the exact copay for lab work at your preferred lab.
Lab Tests Medicare Does Not Cover
Medicare does not cover lab work that is not medically necessary or that is ordered for reasons other than diagnosis, treatment, or monitoring of a medical condition. Tests ordered for employment, insurance, legal proceedings, or immigration purposes are not covered. Routine wellness blood work beyond Medicare's preventive screening list is also not covered.
Some specialized tests — such as genetic testing, certain biomarker panels, or experimental tests — may not be covered unless they meet specific Medicare coverage criteria. If your doctor orders a test you are unsure about, ask whether Medicare covers it before the test is performed. You can also call Medicare at 1-800-MEDICARE to ask about a specific test code.
If a lab test is not covered by Medicare, the lab must give you a notice before the test is performed telling you that you will owe the full cost. This is called an Advance Beneficiary Notice (ABN). You can choose to have the test anyway and pay out of pocket, or decline it.
How to Check Coverage Before Your Lab Work
Before your lab test, you can find out what Medicare will pay by asking your doctor's office or the lab directly. Give them your Medicare number and the specific test code (called a CPT code), and they can tell you whether it is covered and what your coinsurance will be.
You can also check Medicare's coverage yourself using the Medicare Coverage Database at cms.gov, which lists which tests are covered and under what conditions. Search by test name or CPT code. If the test is not listed as covered, the lab should provide an ABN before performing it.
If you have a Medigap or Medicare Advantage plan, contact your plan directly to ask about your specific copay or coinsurance for a particular lab. Your plan may have negotiated different rates than Original Medicare, and knowing your plan's cost-sharing rules before the test is performed helps you budget.
Frequently Asked Questions
Do I have to pay my deductible for every lab test?
No. You pay your Part B deductible once per calendar year, and it applies to all Part B services combined — not per test. Once you have paid $240 (in 2024), you do not pay it again that year. Preventive lab tests do not count toward your deductible; they are covered at no cost regardless.
What if the lab charges more than Medicare approves?
Medicare-participating labs cannot bill you for the difference between what they charge and what Medicare approves. If a lab is not a Medicare participant, you may owe the full charge. Always ask whether the lab participates with Medicare before the test.
Can I get a lab test without a doctor's order?
Medicare does not cover lab work you order yourself without a doctor's order. The test must be ordered by a doctor or other may have access to healthcare provider as part of your care. Direct-to-consumer lab tests are not covered by Medicare.
Will my lab costs count toward my out-of-pocket maximum?
If you have Original Medicare with a Medigap plan, there is no out-of-pocket maximum — you are responsible for costs until your Medigap plan covers them. If you have Medicare Advantage, your lab coinsurance and copays do count toward your plan's out-of-pocket maximum, and once you reach it, your plan covers 100 percent of covered services for the rest of the year.
Are home lab tests or mail-in tests covered?
Some home lab tests ordered by your doctor may be covered if they meet Medicare's coverage rules for that specific test. Mail-in lab kits sold directly to consumers without a doctor's order are not covered. Ask your doctor whether a home test option is available and whether Medicare covers it before you order.