HCPCS Code G2023: COVID-19 specimen collection billing guide

Key Takeaways

HCPCS Code G2023 covered COVID-19 specimen collection for SARS-CoV-2, from any specimen source, billed by independent labs serving homebound or non-hospital inpatient patients.

G2023 was deleted effective May 12, 2023, when the COVID-19 Public Health Emergency ended. Claims for dates of service on or after that date are not payable.

G2024 was the companion code for non-homebound patients; C9803 applied in hospital outpatient settings. No single universal replacement exists post-PHE.

Pabau’s claims management software helps labs and clinical practices track code status, document correctly, and avoid billing deleted or retired codes.

HCPCS Code G2023 was a Level II G-code used by independent laboratories to bill Medicare and Medicaid for COVID-19 specimen collection from homebound and non-hospital inpatient patients during the federal Public Health Emergency. It was deleted effective May 12, 2023, when the PHE ended.

Claims submitted for any date of service on or after that date are not payable under Medicare or most state Medicaid programs. For independent laboratories that regularly collected COVID-19 specimens from homebound patients, this change required an immediate shift in billing practice with no single direct replacement.

HCPCS Code G2023: Code description and background

HCPCS Code G2023 was a Level II HCPCS code added by the Centers for Medicare and Medicaid Services (CMS) in the Level II quarterly update file in May 2020. According to CMS’s HCPCS program, Level II codes are used to report services and supplies not covered by CPT, including laboratory specimen collection procedures created specifically in response to the COVID-19 pandemic.

The official full descriptor reads:

The phrase “any specimen source” in the descriptor is significant. G2023 covered collection of nasal swabs, throat swabs, saliva samples, and other body fluids used to test for SARS-CoV-2. The code covered the physical act of collecting the specimen, regardless of which collection method was used or which specimen type was obtained.

Labs also had to maintain the patient authorization and data-security practices that sound medical billing processes require alongside this code. The CMS specimen collection fee and associated travel allowance were paid to independent laboratories collecting specimens for COVID-19 clinical diagnostic laboratory testing from beneficiaries who were homebound or non-hospital inpatients.

Who could bill G2023?

CMS restricted G2023 to a specific category of providers. Billing it as a general physician or hospital code was a common error during the pandemic.

• Independent clinical diagnostic laboratories were the primary eligible billers. These are labs that collect specimens but do not perform the testing themselves, or labs that both collect and perform testing.
• Physician practices and non-physician practitioners were generally not eligible to bill G2023 as a standalone code. Physicians collecting specimens during an office visit typically billed CPT code 99000 (handling and/or conveyance of specimen from the office to an outside laboratory) or included the collection in the office visit charge.
• Hospital outpatient departments used HCPCS code C9803 rather than G2023 for COVID-19 specimen collection. G2023 was not assigned a hospital outpatient prospective payment system status indicator for routine use in those settings.
• Testing sites that collected but did not test qualified if they met the independent laboratory criteria under Medicare Part B.

State Medicaid programs sometimes applied different eligibility rules than Medicare. Some allowed physician billing of G2023 under specific circumstances during the PHE. Coders working in states like New York, Texas, or Washington needed to review individual payer policies rather than relying solely on federal Medicare guidance.

Billing guidelines and documentation requirements

Billing G2023 correctly required meeting several concurrent conditions, and missing any one created claim denial risk. Strong home visit billing documentation workflows, supported by reliable AI documentation tools, were essential to meeting these requirements.

Patient status requirements

G2023 was designed for specimen collection from patients who were homebound or non-hospital inpatients. This is the most operationally important rule. A homebound patient, under Medicare’s definition, is one who normally cannot leave home without considerable effort due to illness, injury, or disability.

Documentation in the patient record needed to support the homebound or non-hospital inpatient status, and vague notes were not sufficient. Accurate clinical notes should reflect the patient’s condition and why the laboratory technician traveled to the patient rather than the patient presenting at a collection site.

Travel allowance billing

When an independent laboratory technician traveled to a homebound patient to collect the specimen, labs could also bill a travel allowance alongside G2023. The travel allowance reimbursed the cost of the trip to the patient’s location.

Travel allowance billing has its own complex rules and was subject to CMS-specific conditions. Labs needed to document the travel distance and confirm the patient met homebound criteria before billing both the collection code and the travel allowance on the same claim.

ICD-10 diagnosis codes required

G2023 claims required an appropriate ICD-10-CM diagnosis code to establish medical necessity. The most commonly used codes were:

• Z03.818: Encounter for observation for suspected exposure to other biological agents ruled out
• Z20.828: Contact with and (suspected) exposure to other viral communicable diseases

UnitedHealthcare guidance confirmed that cost sharing was waived for COVID-19-specific specimen collection when billed with G2023 or CPT 99001 alongside the appropriate ICD-10 code, provided the claim was not accompanied by a separate evaluation and management charge.

Payer policies varied, so verifying individual payer bulletins was necessary. Good preventive medicine visit documentation practices supported the audit trail needed to substantiate these claims.

Cost sharing waivers

Under the Families First Coronavirus Response Act and the CARES Act, most payers waived patient cost sharing for COVID-19 specimen collection during the PHE. This applied to G2023 claims in most Medicare and commercial settings, though the specific conditions varied by payer and coverage year.

When was G2023 deleted?

G2023 was deleted effective May 12, 2023. That date corresponds to the official end of the federal COVID-19 Public Health Emergency, which terminated on May 11, 2023. New York State Medicaid guidance explicitly confirms G2023 was active from May 22, 2020 through May 11, 2023, and that the code is no longer payable for dates of service on or after May 12, 2023.

Multiple payer bulletins and state Medicaid programs confirmed this date independently. APS Medical Billing’s post-PHE update confirmed that CPT/HCPCS codes U0003, U0004, U0005, G2023, and G2024 are all no longer payable for dates of service on or after May 12, 2023.

This means:

• Claims for dates of service through May 11, 2023 may still be payable if they meet all applicable billing requirements
• Any claim with a date of service of May 12, 2023 or later should not use G2023
• Retroactive claim review and audits for G2023 claims submitted during the PHE remain possible

Labs and billing departments reviewing open accounts receivable from the PHE period should confirm that all G2023 claims carry dates of service no later than May 11, 2023. A disciplined revenue cycle management process and integrated EHR tools help labs reconcile claim dates against service records accurately.

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G2023 vs. G2024: What is the difference?

G2023 and G2024 were introduced together in the May 2020 HCPCS Level II quarterly update. They cover the same procedure but apply to different patient populations.

G2024 carried the full descriptor: “Specimen collection for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (coronavirus disease [COVID-19]), from an individual in a SNF or by a laboratory on behalf of a HHA, any specimen source.”

In practice, G2024 applied to skilled nursing facility and home health agency settings, while G2023 addressed the homebound patient scenario where a technician traveled to the patient.

Both codes were deleted on the same date and for the same reason. Neither applies to any date of service after May 11, 2023. You can look up their historical descriptors using the AAPC Codify HCPCS lookup tool, which maintains records of deleted codes.

C9803 and hospital outpatient COVID-19 specimen collection

Hospital outpatient departments operated under a different coding framework than independent laboratories during the PHE. HCPCS code C9803 was the relevant code for hospital outpatient COVID-19 specimen collection in many contexts, rather than G2023.

Washington Apple Health (Medicaid) clinical policy documentation explicitly referenced both C9803 and G2023 for specimen collection, confirming that the applicable code depended on the provider type and billing context. CMS assigned a different status indicator to G2023 for hospital outpatient prospective payment system purposes, meaning hospitals could not routinely substitute G2023 for C9803 in outpatient settings.

For billing teams reviewing historical hospital outpatient COVID-19 claims, verifying which code was used and whether it matched the setting is an important part of retroactive audit preparation. Reliable clinical documentation software keeps the records needed for these reviews preserved and accessible.

What replaced G2023 after the PHE ended?

There is no single direct replacement for G2023. The correct approach depends on the clinical scenario and payer.

When the PHE ended, Medicare’s special COVID-19 billing accommodations largely reverted to pre-pandemic rules. For specimen collection billing after May 11, 2023, consider the following:

• Routine specimen collection without specific COVID-19 context: Standard specimen handling codes apply. CPT code 99000 (handling and/or conveyance of specimen from a physician’s office to an outside laboratory) and CPT code 99001 (handling and/or conveyance of specimen from a non-physician source to a laboratory) are relevant depending on the origin of the specimen.
• COVID-19 testing continues as a standard clinical lab service: COVID-19 PCR and antigen tests are now billed under applicable CPT codes (e.g., 87635 for COVID-19 PCR) at standard clinical lab rates. Medicare no longer applies the enhanced PHE reimbursement rates.
• State Medicaid programs vary: Some state programs maintained COVID-19 billing provisions beyond May 12, 2023, or transitioned to standard lab codes at different rates. Verify with individual state Medicaid agencies before billing.
• Homebound patient specimen collection: The regulatory framework for billing a specimen collection fee and travel allowance for homebound patients still exists outside the COVID-19 context, but the specific PHE codes are gone. Labs collecting specimens from homebound patients for other clinical reasons should consult CMS guidance on the general specimen collection fee, alongside any related remote patient monitoring services documented for those patients.

The PGM Billing HCPCS lookup tool can help billing teams verify current code status before submitting claims.

Related COVID-19 billing codes

G2023 was part of a broader set of COVID-19-specific codes created during the pandemic. Understanding how they relate matters for retroactive claim review and audit response.

The CMS HCPCS program page maintains the authoritative list of active and deleted HCPCS Level II codes.

Labs and practices managing ongoing audits benefit from keeping detailed itemized billing records and digital forms for clinical documentation that capture the full specimen collection record, including patient status, collection date, specimen type, and ordering provider. This documentation supports claim defense long after the service date.

How Pabau supports lab billing

Labs and practices that billed G2023 during the PHE face ongoing administrative work: retroactive claim review, audit responses, and transitioning COVID-19 billing workflows to current standard codes. A cloud-based EHR reduces the claim denial and audit risk that comes from billing deleted codes by mistake or failing to document patient eligibility correctly.

Pabau’s claims management software helps practices track claim status, link the correct diagnosis codes to each procedure, and maintain the structured documentation needed to defend claims in audit situations. As a single medical billing system, it lets labs manage specimen collection records, patient data, and billing submissions together, without the fragmentation that increases audit risk.

For practices transitioning from COVID-19 PHE billing to standard clinical coding, Pabau’s structured record-keeping and workflow tools help teams adapt without losing the audit trail. See how Pabau handles lab billing workflows by booking a demo.

Summary

HCPCS Code G2023 reimbursed independent laboratories for collecting COVID-19 specimens from homebound and non-hospital inpatient patients during the federal Public Health Emergency. Its deletion on May 12, 2023 was universal across Medicare and most state Medicaid programs.

For billing teams, verify that no G2023 claims carry a date of service on or after May 12, 2023, and that retroactive audit requests are supported by documentation establishing patient homebound status, specimen type, and collection date.

Post-PHE specimen collection billing returns to standard CPT and HCPCS frameworks — there is no single replacement code. Standard coding references and Pabau’s claims management tools can help manage this transition.

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