605 Denial Code — Meaning, Causes & Resolution Guide

📋What Does 605 Mean? A Full Explanation

Denial code 605 is a Claim Adjustment Reason Code (CARC) used on the 835 electronic remittance advice and Explanation of Benefits (EOB) to communicate why a claim or service line was adjusted from the billed amount. This code is standardized by X12 and used consistently by Medicare, Medicaid, and commercial payers across all HIPAA-compliant transactions.

When this code appears on your remittance, it signals a specific issue that caused the payer to pay a different amount than billed. Identifying the root cause tied to this code is the first step toward correcting the claim, resubmitting, or filing an appeal to recover lost reimbursement.

⚠️Common Reasons You Received Denial Code 605

• →Missing, invalid, or incomplete information on the claim
• →Billing code mismatch or modifier inconsistency
• →Service not covered under the patient's plan on the date of service
• →Authorization or referral not obtained prior to treatment
• →Duplicate claim submission or previously adjudicated service

✅How to Resolve and Fix a 605 Denial

• 1Review the full ERA/EOB for any accompanying Remark Codes (RARC) which provide additional detail about the specific issue.
• 2Verify the patient's eligibility, coverage, and benefits for the date of service in question.
• 3Identify and correct any claim errors — wrong codes, missing modifiers, incorrect dates, or missing authorization numbers.
• 4Gather supporting documentation (medical records, auth, referral, ABN) required for appeal or corrected claim.
• 5Resubmit a corrected claim or file a formal appeal with the payer within their specified deadline (typically 90–180 days).

💰Who Pays? Financial Responsibility for Code 605

The Group Code paired with 605 on the remittance determines who is financially responsible for the adjusted amount. Always check the accompanying Group Code before billing the patient or writing off the balance.

📨How to Appeal a 605 Claim Denial Effectively

Appealing a 605 denial requires a timely, well-documented response. Most payers require appeals within 30 to 180 days of the remittance date — missing this window typically results in a final denial. Start by reviewing the payer's provider manual for the specific appeal process and required forms.

Your appeal package should include a clear cover letter referencing the original claim number and denial date, corrected claim information if applicable, relevant medical records or clinical notes supporting medical necessity, and copies of the original claim and remittance advice. Submit via certified mail or the payer portal and retain confirmation of receipt.

❓Frequently Asked Questions — Denial Code 605