Denial Code PR-55
Procedure/treatment/drug is deemed experimental/investigational by the payer.
Source: X12 Claim Adjustment Reason Codes (CARC) & Group Codes. Maintained by the D3rx Clinical Billing Team.
What PR-55 means
The payer considers the service experimental or investigational, and under the PR group code the patient is responsible — typically because the patient was notified in advance and accepted the cost. Confirm valid advance notice before billing them.
Why PR-55 happens
- An experimental/investigational service the patient elected after advance notice (ABN/financial waiver)
- Off-label or emerging treatment not covered, billed to the patient on notice
- A non-covered investigational drug or device the patient agreed to pay for
- A service the payer's policy lists as investigational, with patient liability accepted
What to do when you get PR-55
- 1Confirm valid advance notice (ABN/financial waiver) is on file before billing the patient
- 2Verify the payer's policy actually classifies the service as experimental/investigational
- 3If the service should be covered for this indication, appeal with clinical evidence instead
- 4If non-coverage stands and notice was given, bill the patient
Got this denial right now?
Generate a patient-balance explainer letter — free
PR-55 is the patient's responsibility. Generate a clear, plain-English balance letter — free, no signup.
PR group code: who absorbs the charge
Patient Responsibility — May be billed to the patient.
A PR adjustment is the patient's liability — a deductible, coinsurance, copay, or a non-covered amount the patient owes. It is collectible directly from the patient, ideally after advance notice for any non-covered service.
Appeal, correct, or write off PR-55?
PR-55 is collectible from the patient only when they were properly notified that the service was investigational and likely non-covered. First decide whether to fight coverage: if recent evidence/guidelines support the service for this indication, appeal with that documentation (a stronger play than billing the patient). If the investigational determination stands and advance notice exists, the balance is the patient's.
Timing & deadlines
If appealing coverage, use the payer's window (commercial ~180 days from the remittance; Medicare-related plans 120 days for redetermination). There is no payer deadline on collecting a legitimate PR balance once advance notice is confirmed.
Example
A patient elects an investigational treatment after signing a financial waiver acknowledging likely non-coverage. The payer returns PR-55, and because valid advance notice exists, the practice bills the patient — unless evidence supports appealing the investigational determination.
Prevent PR-55 going forward
- Obtain a signed ABN/financial waiver before any likely-investigational service
- Check the payer's experimental/investigational policy in advance
- Give patients a clear cost estimate for non-covered investigational care
- Document the evidence basis in case an appeal is the better path
Code families most affected
- Emerging genetic/molecular diagnostics
- Newer devices and off-label treatments
- Non-covered investigational drugs and biologics
Related codes
Payer notes
CARC 55 carries the PR group code when the patient was notified and accepts liability for the investigational service; without valid advance notice it generally falls under CO-55 (provider write-off). Verify the notice before billing the patient.
Explain this PR-55 balance to your patient
PR-55 is a patient-responsibility balance. D3rx drafts a clear, plain-English patient-balance explainer for PR-55 — free, no signup.
Medical billing disclaimer
CARC/RARC definitions are the standardized X12 set; group-code semantics follow the X12 Claim Adjustment Group Code standard. Filing and appeal windows vary by payer — the standard anchors shown (Medicare redetermination 120 days from the remittance; Medicare timely filing 12 months from date of service; most commercial payers ~90-180 days) are general references, not a guarantee for any specific plan. Always confirm the rule in the payer's provider manual before acting. D3rx is not responsible for claim outcomes.