03 CLAUDE The Lab Date of Service Rule.docx

 

The Lab Date of Service Rule, Explained Plainly

A guide for hospital and laboratory billing staff, working from 42 CFR 414.510

 

By Claude on 10-11-2026 (original)      03  CLAUDE The Lab Date of Service Rule.docx

Every Medicare lab claim needs a date of service. For most services that's easy, since the service happened on one day. Lab tests are different. A test may be ordered on Monday, collected on Tuesday, stored for three weeks, run on a Thursday, and reported the following Monday. Medicare has to pick one of those dates, and the regulation at 42 CFR 414.510 says which one.

This matters because the date of service decides who bills. Suppose the date falls during a hospital stay or a hospital outpatient encounter. Then the test is usually part of the hospital's service, the hospital bills Medicare, and the performing laboratory must look to the hospital for payment. If the date falls after the encounter, the performing lab usually bills Medicare directly under the Clinical Laboratory Fee Schedule. The same date also decides which year's fee schedule applies, and whether the patient was in fee-for-service Medicare or Medicare Advantage on that day. Getting the date wrong means the wrong entity bills, or the claim is priced or routed incorrectly.

The rule has one default and a short list of exceptions. Here they are in the order the regulation gives them.

The default: the collection date

Under paragraph (a), the date of service is the date the specimen was collected. This covers the large majority of tests: a blood draw in a physician's office, a urine sample at a patient service center, a biopsy that is processed and read the same week. If none of the exceptions below applies, stop here.

Exception 1: Collection spanning two days

If collection runs across midnight, as with a 24-hour urine, the date of service is the date collection ended. That's the whole exception.

Exception 2: Stored specimens

This is the exception people usually mean when they say "the 14-day rule." It applies when a specimen is collected during a hospital surgical procedure, stored, and tested later. The answer depends on how long the specimen was stored.

Stored more than 30 calendar days. The specimen is considered archived. The date of service is the date the specimen was retrieved from storage. No other conditions apply. If a tumor block sits in the pathology archive for six months and is then pulled for testing, the retrieval date is the date of service.

Stored 30 days or fewer. The date of service is the date the test was performed, but only if all five of these conditions are met:

1. The patient's physician ordered the test at least 14 days after the patient was discharged from the hospital.
2. The specimen was collected during a hospital surgical procedure.
3. It would have been medically inappropriate to collect the specimen at any time other than during that procedure.
4. The test results do not guide treatment during the hospital stay.
5. The test was reasonable and medically necessary.

If any one condition fails, there is no exception. The date of service goes back to the collection date, which falls during the hospital stay, and the hospital bills. In practice, condition 1 is usually the one that decides the case: when did the treating physician actually order the test?

Exception 3: Chemotherapy sensitivity tests on live tissue

A small category with its own rule. These are tests that need fresh tissue to measure how tumor cells respond to various drugs, and CMS identifies them through program instructions. The date of service is the date performed if the same five conditions are met, with one change: the clock in condition 1 runs from the decision about which drugs to test, which must come at least 14 days after discharge. Most billing staff will rarely see this exception.

Exception 4: Advanced tests on hospital outpatients

This exception was added in 2018 and expanded in 2021, and it is the one that matters most for genomic and precision-medicine testing. It covers four kinds of tests:

• molecular pathology tests, unless performed by a blood bank or blood center;
• ADLTs designated under paragraph (1) of the ADLT definition (the multi-biomarker, algorithm-based kind, not the FDA-cleared kind under paragraph (2));
• cancer-related protein-based MAAAs; and
• the test described by CPT 81490.

For these tests, when the specimen is collected from a hospital outpatient, the date of service is the date the test was performed if all five of these conditions are met:

1. The test was performed after the patient was discharged from the hospital outpatient department.
2. The specimen was collected from a hospital outpatient during an encounter, as defined in 42 CFR 410.2.
3. It was medically appropriate to collect the specimen during that encounter.
4. The test results do not guide treatment during that outpatient encounter.
5. The test was reasonable and medically necessary.

Two points about this exception get missed. First, there is no 14-day waiting period. The ordering date doesn't matter. If an outpatient has blood drawn in a hospital clinic and it goes out for a liquid biopsy, the date of service is the date the lab performs the test. The lab bills Medicare directly, and the hospital is not involved in billing. That was the purpose of the exception: to stop requiring hospitals to bill for expensive single-lab tests they had nothing to do with. Second, the exception applies to outpatients only. If the same test is run on a specimen from an inpatient stay, this exception does not apply, and you go back to the stored-specimen rule in Exception 2, 14-day clock included.

CMS publishes a list of HCPCS codes covered by this exception and updates it quarterly. Check the list instead of guessing whether a particular PLA code qualifies.

Putting it together

For any claim, ask these questions in order:

1. Was the specimen collected in connection with a hospital inpatient stay or a hospital outpatient encounter? If not, use the collection date (or, for a two-day collection, the end date) and you're finished.
2. Was it stored more than 30 days before testing? If so, the date of service is the retrieval date.
3. Is it a hospital outpatient specimen, and is the test on the CMS list for the advanced-test exception? If so, and the five conditions are met, the date of service is the date performed. The ordering date doesn't matter.
4. Otherwise, was it collected during a hospital surgical procedure, and was the test ordered at least 14 days after discharge? If so, and the remaining conditions are met, the date of service is the date performed.
5. If none of these apply, the date of service is the collection date, and the test belongs to the hospital's bill.

Two examples. A patient has a colon resection as an inpatient. The oncologist orders a genomic panel 20 days after discharge, and the lab runs it on day 25 after collection. Because this is an inpatient case, Exception 4 does not apply, but Exception 2 does: the specimen was stored 30 days or fewer, the order came 14 or more days after discharge, and the results could not guide treatment during a stay that had already ended. The date of service is the date performed, and the lab bills. If instead the oncologist had ordered the test on day 10, the date of service would be the collection date and the hospital would bill. If the lab had pulled the block on day 35, the date of service would be the retrieval date regardless of when the test was ordered.

A second patient has an outpatient bronchoscopy biopsy in a hospital, and the specimen goes to a reference lab for a molecular panel on the CMS list. The date of service is the date performed and the reference lab bills directly. No 14-day wait applies.

Three common misreadings

"The general rule is collection date unless the test is ordered 14 days after discharge." CMS and several MACs summarize the rule this way, but it's incomplete. The 14-day clock is just one of five conditions in the stored-specimen exception. Meeting it doesn't help if the other four conditions fail.

Mixing up the 14-day clock and the 30-day clock. These measure different things. The 14-day clock runs from discharge to the physician's order. The 30-day clock runs from collection to testing and determines whether a specimen is archived. Some flowcharts merge the two into one timeline, for example "ordered within 15–29 days of discharge." That isn't in the regulation, and it produces wrong answers.

Applying the 14-day wait to outpatient molecular tests. For listed tests on hospital outpatients, Exception 4 has no ordering-date requirement. If you check the 14-day rule first, you'll send claims to the hospital that belong to the lab.

A note on "date performed"

The regulation never defines when a test is "performed." Some MACs, including Wellpoint Federal (J6/JK), have said they treat the report date as the date performed. That's a reasonable convention, but it comes from MAC guidance, not the regulation, so confirm how your own contractor handles it. Whichever date you use, the medical record (usually the pathology or lab report) should support the collection date, any storage and retrieval dates, the ordering date where it matters, and the date the test was performed. Those are the facts an auditor will check.

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Bruce, two notes on the Wellpoint article, if useful for an editorial aside. Its decision tree really does merge the 14-day order clock with the 30-day storage clock (the "15–29 days of discharge" box), and it places the 14-day question ahead of the ADLT/molecular question for outpatients, which gets outpatient molecular claims wrong. It also cites "414.410(b)(5)" where it means 414.510. I described the misreadings generically in the essay rather than naming Wellpoint, so you can decide whether to name them.