TL;DR: Aetna, a CVS Health company, modified CPB 0466 covering routine patient care costs in clinical trials, effective September 26, 2025. Here's what billing teams need to know about the affected HCPCS codes and how to handle claims correctly.
CPB 0466 Aetna governs whether costs tied to a patient's participation in a clinical trial get covered as routine care — or don't. This update touches eight HCPCS codes, including S9988, S9990, S9991, S9992, S9994, S9996, and modifiers Q0 and Q1. If your practice or facility bills for patients enrolled in clinical trials, this coverage policy directly affects your claim strategy and your exposure to denials.
Quick-Reference Table
| Field | Detail |
|---|---|
| Payer | Aetna, a CVS Health company |
| Policy | Clinical Trials, Coverage of Routine Patient Care Costs |
| Policy Code | CPB 0466 |
| Change Type | Modified |
| Effective Date | September 26, 2025 |
| Impact Level | High |
| Specialties Affected | Oncology, hematology, neurology, and any specialty running or supporting Phase I–III clinical trials |
| Key Action | Audit your clinical trial billing workflows before September 26, 2025 and confirm modifier Q0 vs. Q1 usage on all affected claims |
Aetna Clinical Trial Coverage Criteria and Medical Necessity Requirements 2025
The Aetna clinical trials coverage policy distinguishes between two types of services: routine clinical services and investigational clinical services. That distinction drives everything in your billing workflow.
Routine patient care costs are the services a patient would receive even if they weren't in a trial — standard labs, imaging, office visits, and treatments tied to managing a condition. Aetna covers these when they meet medical necessity criteria and fall within the scope of what CPB 0466 defines as routine care. The phrase "routine patient care costs" is the fulcrum of this policy.
Investigational services are a different story. Services provided specifically because of the trial protocol — not because of standard care — don't meet Aetna's medical necessity standard under this policy. Billing those as routine care is the fastest path to a claim denial.
Prior authorization requirements under this policy are real. If your patients are enrolled in a clinical trial and you're billing Aetna, confirm prior auth requirements on a per-plan basis before submitting. Not every Aetna plan behaves the same way on clinical trial coverage, and the consequences of getting it wrong show up on your accounts receivable.
The policy uses modifier Q0 and modifier Q1 to distinguish between investigational and routine services. Modifier Q0 flags an investigational clinical service provided in an approved clinical research study. Modifier Q1 flags a routine clinical service provided in the same setting. Using the wrong modifier is not a minor clerical error — it determines whether the claim pays or denies.
Aetna Clinical Trial Exclusions and Non-Covered Indications
Three HCPCS codes land squarely in the non-covered column under CPB 0466, and they represent costs that feel like they should be reimbursable. They're not.
S9992 covers transportation costs to and from the trial location, including local fares like taxis. Aetna explicitly excludes this from coverage under this policy.
S9994 covers lodging for the clinical trial participant and one caregiver or companion. Also excluded.
S9996 covers meals for the participant and caregiver. Also excluded.
This is the part where billing teams sometimes push back. These are real costs that patients incur because of the trial. But Aetna's coverage policy draws a hard line here: ancillary trial participation costs — transportation, lodging, meals — are not covered. If your billing team has been submitting these codes and getting paid, check your remittance history. Overpayments create compliance exposure.
The real issue here is patient communication. Someone on your team needs to tell patients that these costs won't be reimbursed by Aetna before they incur them. Clinical trial coordinators and financial counselors should know this policy by name.
Coverage Indications at a Glance
| Indication | Status | Relevant Codes | Notes |
|---|---|---|---|
| Routine clinical services in an approved clinical research study | Covered (when medical necessity criteria are met) | Modifier Q1, S9990, S9991 | Confirm prior authorization; routine care must meet medical necessity standard |
| Investigational clinical services in an approved clinical research study | Not covered as routine care | Modifier Q0 | Flagged investigational; billed separately per protocol |
| Services provided as part of a Phase I clinical trial | Related code — coverage determined per indication | S9988 | Phase I services face the highest scrutiny; confirm plan-level coverage before billing |
| Services provided as part of a Phase II clinical trial | Related code — coverage determined per indication | S9990 | Distinguish routine vs. investigational components |
| Services provided as part of a Phase III clinical trial | Related code — coverage determined per indication | S9991 | Phase III generally has better coverage precedent, but still requires documentation |
| Transportation costs to/from trial location | Not covered | S9992 | Explicitly excluded under CPB 0466 |
| Lodging for participant and caregiver | Not covered | S9994 | Explicitly excluded under CPB 0466 |
| Meals for participant and caregiver | Not covered | S9996 | Explicitly excluded under CPB 0466 |
Aetna Clinical Trial Billing Guidelines and Action Items 2025
The effective date of September 26, 2025 is your deadline. Here's what to do before it arrives.
| # | Action Item |
|---|---|
| 1 | Audit every open clinical trial case in your system. Pull all claims billed with S9988, S9990, S9991, and modifiers Q0 and Q1 from the past 12 months. Look at whether routine and investigational services were correctly separated. If they weren't, you have a modifier correction and potentially a refund exposure to address. |
| 2 | Stop billing S9992, S9994, and S9996 to Aetna. These codes are not covered under CPB 0466. If your charge capture system still includes them as billable options for Aetna patients in clinical trials, remove them or add a hard stop before September 26, 2025. Claims with these codes will deny. |
| 3 | Train your clinical trial coordinators and billing staff on the Q0/Q1 distinction. Modifier Q0 goes on investigational services. Modifier Q1 goes on routine services. This is not optional cleanup — it's the structural logic of clinical trial billing under this policy. A one-hour training session before the effective date is worth more than two weeks of denial rework. |
| 4 | Confirm prior authorization requirements on a per-plan basis. Aetna plan designs vary. Self-funded employer plans may carve out clinical trial coverage differently than fully insured plans. Before billing for any patient enrolled in a clinical trial, verify whether prior auth is required for that specific plan. Don't assume because one plan approved it that another will. |
| 5 | Update your financial counseling scripts for clinical trial patients. Patients need to know that S9992 (transportation), S9994 (lodging), and S9996 (meals) are not covered by Aetna under CPB 0466. Build that disclosure into your pre-enrollment financial counseling process. If patients are expecting reimbursement for those costs, the conversation is easier before the bill than after. |
| 6 | Review your clinical trial agreements with research sponsors. Many sponsor agreements include provisions for costs not covered by insurance. If Aetna won't reimburse transportation, lodging, or meals, the sponsor protocol may cover them through a separate mechanism. Your billing team and research finance team need to coordinate on this. |
| 7 | If you're uncertain how this applies to your patient mix, talk to your compliance officer before September 26, 2025. Clinical trial billing sits at the intersection of coverage policy, research compliance, and fraud and abuse law. The rules are specific and the exposure is real. This is not a policy change to interpret alone. |
| Previous Version | Current Version |
|---|---|
| Coverage is considered experimental and investigational for all indications | Coverage is considered medically necessary when specific criteria are met |
| Prior authorization is not required | Prior authorization is required for initial treatment |
| Documentation must include clinical history | Documentation must include clinical history |
| Re-review every 24 months | Re-review every 12 months with updated clinical documentation |
CPT, HCPCS, and ICD-10 Codes for Clinical Trial Routine Patient Care Costs Under CPB 0466
Covered HCPCS Codes — Routine and Related Clinical Trial Services
| Code | Type | Description |
|---|---|---|
| Modifier Q1 | HCPCS Modifier | Routine clinical service provided in a clinical research study that is in an approved clinical research program |
| S9988 | HCPCS | Services provided as a part of a Phase I clinical trial |
| S9990 | HCPCS | Services provided as a part of a Phase II clinical trial |
| S9991 | HCPCS | Services provided as a part of a Phase III clinical trial |
| Modifier Q0 | HCPCS Modifier | Investigational clinical service provided in a clinical research study that is in an approved clinical research program |
Note: Coverage status for S9988, S9990, and S9991 depends on whether the services meet medical necessity criteria and whether they are classified as routine vs. investigational under CPB 0466. Modifier Q0 and Q1 determine that classification.
Not Covered HCPCS Codes Under CPB 0466
| Code | Type | Description | Reason |
|---|---|---|---|
| S9992 | HCPCS | Transportation costs to and from trial location and local transportation costs (e.g., fares for taxi) | Explicitly excluded under CPB 0466 — not covered for indications listed in the CPB |
| S9994 | HCPCS | Lodging costs (e.g., hotel charges) for clinical trial participant and one caregiver/companion | Explicitly excluded under CPB 0466 — not covered for indications listed in the CPB |
| S9996 | HCPCS | Meals for clinical trial participant and one caregiver/companion | Explicitly excluded under CPB 0466 — not covered for indications listed in the CPB |
No ICD-10-CM codes are listed in the CPB 0466 policy data. Clinical trial billing guidelines under this policy are driven by service type and modifier assignment, not diagnosis code.
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