Home 5 News 5 Labs Should Be Wary of Improper Billing of G0483 Testing

Labs Should Be Wary of Improper Billing of G0483 Testing

by | Mar 10, 2023 | News, Open Content

Recent OIG report says Medicare could have saved up to $215.8 million on at-risk payments for G0483 definitive drug tests.

In 2021, the U.S. Department of Health and Human Services Office of Inspector General (OIG) published a report warning of the risk of overpayments for G0483 definitive drug tests and calling on the Centers for Medicare & Medicaid Services (CMS) to manage the risk.1 However, those recommendations went largely unheeded. And now OIG has published a new report finding that, had proper program safeguards been in place, Medicare could have saved up to $215.8 million on at-risk payments for G0483 definitive drug tests that may not have been medically necessary over a five-year period.2 Here’s a briefing on the new OIG report and what it may portend for labs that provide definitive drug tests for Medicare beneficiaries.

G0483 Definitive Drug Test Billing

Medicare pays for drug testing to detect the presence or absence of drugs in patients undergoing treatment for pain management or substance use disorders. That includes:

G0483 Procedure Code Descriptor

“Drug test(s), definitive, utilizing (1) drug identification methods able to identify individual drugs and distinguish between structural isomers (but not necessarily stereoisomers), including, but not limited to GC/MS (any type, single or tandem) and LC/MS (any type, single or tandem and excluding immunoassays (e.g., IA, EIA, ELISA, EMIT, FPIA) and enzymatic methods (e.g., alcohol dehydrogenase), (2) stable isotope or other universally recognized internal standards in all samples (e.g., to control for matrix effects, interferences, and variations in signal strength), and (3) method or drug-specific calibration and matrix-matched quality control material (e.g., to control for instrument variations and mass spectral drift); qualitative or quantitative, all sources, includes specimen validity testing, per day; 22 or more drug class(es), including metabolite(s) if performed.”3

Source: Codify by AAPC
  • Presumptive drug tests, or initial screens indicating whether a sample is positive or negative for a class of drugs, such as opiates; and
  • Definitive drug tests to identify the specific drugs or metabolites present

Definitive tests are deemed medically necessary only when the presumptive test produces an unexpected result. The definitive test is then performed to determine the reason for that result, for example, what drug was contained in the sample of a patient whose presumptive test result came back positive. Definitive testing is not medically necessary on a routine basis or simply to check the accuracy of a presumptive test.

The more drug classes tested for, the higher the Medicare Part B reimbursement amount. The highest reimbursing and one of the most commonly performed definitive drug tests is billed under procedure code G0483 covering 22 or more different drug classes.

The audit that led to the above-mentioned 2021 report confirmed the OIG’s suspicions that providers may be routinely billing for medically unnecessary G0483 definitive tests to take advantage of the high reimbursement rate.

Procedure Codes Used to Bill for Definitive Drug Testing Services

Procedure CodeNumber of Drug Classes2020 Clinical Laboratory Fee Schedule Payment
G04801 – 7$114.43
G04818 – 14$156.59
G048215 – 21$198.74
Source: U.S. Department of Health and Human Services Office of Inspector General (OIG), “Medicare Could Have Saved up to $216 Million over 5 Years If Program Safeguards Had Prevented At-Risk Payments for Definitive Drug Testing Services.” February 2023.2

The New OIG Audit

Unlike the previous audit which was limited to testing on beneficiaries with substance use disorders, the new audit covers definitive drug testing provided to all Medicare beneficiaries over a five-year period from January 2016 through December 2020. During this audit period, Medicare Part B paid approximately $3 billion for definitive drug tests billed by 8,663 providers to 3.3 million beneficiaries, most of whom were receiving treatment for pain management.

The auditors focused on the 1,062 providers it deemed to be “at-risk,” i.e., those that used code G0483 to bill for 75 percent or more of the definitive drug tests they provided and received at least $5,000 for those services during the audit period. Medicare Part B paid those at-risk providers $760.8 million for 3.4 million definitive drug tests provided to 805,080 beneficiaries, with $704.2 million, over 90 percent, of those payments made under code G0483. By contrast, the OIG found that only 21 percent of the 13.7 million definitive drug tests provided by the 4,227 other providers—i.e., the not at-risk providers—were billed under G0483.

The OIG suggests that the at-risk providers may have billed G0483 definitive testing for 22+ drug classes as a matter of routine, rather than basing the determination of how many drug classes needed to be tested based on the presumptive test results, as required by Medicare rules. After all, the providers, patients, and testing frequencies were pretty similar. So, why couldn’t the at-risk group bill the lower reimbursing codes at the same frequencies as the other provider group did?

While CMS was able to identify G0483 overpayments via Comprehensive Error Rate Testing (CERT) review, post-payment reviews, and other oversight activities, the OIG found that these “safeguards were not adequate to prevent or detect [at-risk G0483 payments] to at-risk providers.” Had CMS focused on at-risk payments to at-risk providers, Medicare could have saved up to $215.8 million during the audit period, the report concludes.

The OIG’s Recommendations

The report recommends that CMS take four actions to reduce the risk of G0483 overpayments:

OIG Recommendation 1: Expand program safeguards to prevent and detect at-risk G0483 payments to at-risk providers.

CMS Response: CMS concurred with the recommendation to the extent that additional safeguards would be “feasible, given available resources and expected return.”

OIG Recommendation 2: Review G0483 payments made to at-risk providers during and after the OIG audit period to determine whether they complied with Medicare requirements and, if not, recover any resulting overpayments.

CMS Response: CMS rejected the recommendation, noting that detecting improper G0483 payments would require medical record review of all at-risk providers, which is a resource-intensive process. We don’t think it would be worthwhile to expend these resources, CMS added, especially since we don’t agree with your characterization of providers as being at-risk based only on how frequently they billed G0483 as compared to their peers.

OIG Recommendation 3: Invoke the overpayments process by notifying providers that CMS thinks may have received overpayments to exercise reasonable diligence to identify, report, and return such overpayments in accordance with the 60-day rule. (See the related story4).

CMS Response: CMS didn’t concur with the recommendation, saying it doesn’t believe that the OIG audit constitutes credible information of overpayments. The report points to the risk of overpayments without identifying any particular overpayments actually made. As a result, CMS concluded that the audit “is not sufficient basis upon which CMS can support a 60-day rule notice to identified providers.” The OIG expressed disagreement with that conclusion.

OIG Recommendation 4: Educate providers that received noncompliant payments about Medicare requirements for definitive drug testing services.

CMS Response: CMS didn’t say whether it concurred with this recommendation but did note that it has already issued national provider education on Medicare rules for urine drug testing and that it will continue to educate providers, such as by sending at-risk providers a comparative billing report).

What It Means to Your Lab

The OIG report and subsequent actions that CMS takes in response to it will have the most impact on labs that receive 75 percent or more of their Medicare definitive drug test payments for tests billed under G0483—unless those payments are less than $5,000. As “at-risk providers,” those labs have a target on their backs. Labs currently considered “other providers” might want to keep that 75 percent threshold in mind so that they don’t become “at-risk.”

As CMS stresses in its response to the OIG report, being labeled as “at-risk” doesn’t prove that the lab actually received improper payment for G0483 tests. But that doesn’t mean CMS is taking the OIG report lightly. While apparently unwilling to take the OIG’s recommendations of initiating medical review or activating the 60-day overpayment rule process against “at-risk” providers, CMS reassured the agency that it has and will continue to take other measures to prevent and detect improper G0483 payments, including automated system edits within the claims processing system, pre- and post-payment review, and use of the Fraud Prevention System to alert Medicare Administrative Contractors (MACs) of providers “who bill at an anomalous rate.” MACs and other contractors have already recovered $10.8 million in improper G0483 payments via post-payment reviews, CMS adds.


Billing Medicare for G0483 tests at abnormally high frequencies isn’t illegal, but it is enough to raise a red flag with MACs and the OIG. So, if your lab is at, above, or even near that 75 percent threshold, it’s absolutely imperative to ensure that you have documentation justifying the G0483 tests you bill to Medicare. Specifically, you must be able to show, based on the results of the presumptive test, that it was medically necessary to not only perform definitive testing but also G0483 tests targeting 22 or more different drugs.

Bottom Line: High frequency billing of G0483 testing is perfectly legal as long as you can show that each test performed meets Medicare requirements and wasn’t just performed and billed as a matter of routine.


  1. https://oig.hhs.gov/oas/reports/region9/92003017.asp
  2. https://oig.hhs.gov/oas/reports/region9/92103006.pdf
  3. https://www.aapc.com/codes/hcpcs-codes/G0483
  4. https://www.g2intelligence.com/proposed-rule-puts-labs-at-greater-risk-of-fca-liability/