Medicare Denied Lab Work or Diagnostic Test

What This Means

Your Medicare Summary Notice or Explanation of Benefits shows a denied test. The provider’s billing record may include CARC 50 for a medical-necessity denial or CARC 167 for a diagnosis that did not meet a coverage rule. A code mismatch is one possible cause; missing records, frequency limits and other coverage requirements can also matter. Start by calling the clinician who ordered the test. Ask them to review the diagnosis and medical record, then send any supported correction or missing information to the lab or other provider that billed it.

With Original Medicare, if a required Advance Beneficiary Notice (ABN) was not given before a test expected to be denied as not medically necessary, you generally cannot be billed. Check the MSN’s patient-responsibility amount and ask the billing office for a copy of any ABN. A signature alone does not establish that the notice was valid. Services excluded by law or outside a Medicare benefit category have different rules; experimental lab tests denied as not reasonable and necessary can still require an ABN (CMS notice rules). Medicare Advantage does not use this ABN process — check the plan’s denial notice and ask its member services team who is responsible for the charge.

Check the appeal deadline now: 120 days from receipt of the MSN for Original Medicare, with receipt presumed 5 days after its date unless there is evidence otherwise, or 65 days from the date on a Medicare Advantage denial notice. Follow your notice’s filing instructions. Do not let a correction request run past that deadline. An Original Medicare reopening request does not pause the appeal period (CMS appeals manual, reopening rules, Medicare Advantage appeals).

With Original Medicare, you usually pay nothing for Medicare-covered diagnostic laboratory tests. Other diagnostic services, such as imaging, can have different cost sharing; check which service was billed.

Not sure this is your situation? “Lab test denied” catches searches that belong on a neighboring guide:

• Was the denied service not a lab or diagnostic test — an office visit, a procedure, or therapy turned down as not medically necessary? See not medically necessary.
• Does your notice say your diagnosis itself isn’t covered for the service, whatever the service was? See diagnosis not covered.
• Was it a screening you expected to be free — a cholesterol, diabetes, or cancer screening? See preventive service denied.

This doesn’t necessarily mean the test wasn’t needed. It may mean the paperwork didn’t support coverage under Medicare’s specific rules.

Why This Happens

• The claim did not meet a coding or coverage rule. National and Local Coverage Determinations (NCDs and LCDs) describe coverage requirements. Most local diagnosis-code lists are in related Billing and Coding Articles; lab NCDs have separate dated code lists. Ask the billing office to check the applicable policy, coding guidance and clinical record together.
• The test exceeded a frequency limit. Some tests have coverage frequency limits. Ask which limit applies to your specific test and whether the clinical record supports an exception; screening schedules and diagnostic testing rules can differ.
• The test was considered screening, not diagnostic. Medicare draws a line between “screening” tests (checking for a disease when you have no symptoms) and “diagnostic” tests (investigating a specific symptom or condition). Some screening tests are only covered on a set schedule or not at all.
• Missing or incomplete documentation. The lab or your doctor’s office may not have submitted enough information to support medical necessity.
• The test does not meet a coverage requirement. A service may be excluded or fail a benefit or medical-necessity requirement. The absence of a specific NCD or LCD does not by itself mean Medicare cannot cover it; ask which rule was used to deny your claim.

Should You Appeal?

What To Do Next

1. Check the notice and any ABN. For Original Medicare, compare the bill with the MSN and obtain the ABN if the lab says you accepted responsibility. Check the test, reason, estimated cost and option selected. Option 1 requests a Medicare decision you can appeal; Option 2 does not request a claim decision. If a required valid ABN was missing, raise that with the billing office. For Medicare Advantage, use the plan notice and call member services; ABNs do not apply.
2. Contact the ordering clinician. Ask them to review the record and send accurate diagnostic information to the lab or other provider that billed the test. The billing entity can translate supported clinical information into the appropriate code; it must not invent a diagnosis or change one solely for payment.
3. Ask for the claim details. Get the test name, CPT/HCPCS procedure code, diagnosis code, date of service and exact denial reason. Ask whether the issue is a missing record, a claim error, a coverage rule or a frequency limit.
4. Protect the appeal deadline. If you disagree with the denial, follow the notice instructions on time, even if a correction is still pending. Ask your clinician for relevant records and an explanation of how the test met the coverage requirements.
5. Check the policy and code version for the test date. Use the CMS Medicare Coverage Database for the applicable NCD, LCD and related Billing and Coding Article, and the dated lab NCD code lists where relevant. Ask the billing office to check the version effective on your date of service and whether a later CMS update supports an adjustment. Updates can add or remove codes; a new list does not guarantee your claim will be paid.
6. Get free help. Contact your State Health Insurance Assistance Program (SHIP) or call 1-800-MEDICARE (1-800-633-4227).

Sources

• Medicare.gov: Diagnostic Laboratory Tests
• CMS: Medicare Coverage Database — NCDs and LCDs
• CMS: Medicare Coverage Determination Process
• CMS: Local Coverage Determinations
• CMS: ABN tutorial — Original Medicare scope, required notice details and options.
• CMS: Claims Processing Manual, chapter 30 — required and optional ABN uses, including experimental tests.
• 42 CFR 410.32 — ordering-clinician and billing-laboratory documentation requirements.
• CMS: Laboratory negotiated-rulemaking final rule — laboratories may translate supported diagnostic narratives into codes.
• CMS: CR14614, laboratory coding update — code-specific effective dates can differ from software implementation; affected claims brought to the contractor’s attention can be adjusted.

Frequently Asked Questions