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[California] Update: Unpaid Medicare cost share will be reported with CARC 303
Act
by Nov 30, 2026
Effective date
Nov 30, 2026
Identified
Oct 31, 2026
Summary
Anthem Blue Cross will report unpaid Medicare cost share amounts using CARC 303 with Group Code CO on remittance advice for California Medicare Advantage claims finalized by November 30, 2026. Billing teams must verify QMB eligibility, avoid collecting these amounts from patients, and refund any incorrect patient payments, as balance-billing protections apply regardless of Medicaid payment status.
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What to do
by Nov 30, 2026 · 5 steps
01Billing team must implement the following operational changes for California Medicare Advantage patients.
02Verify Qualified Medicare Beneficiary (QMB) eligibility for the date of service before billing.
03Configure billing system and staff workflows to recognize CARC 303 with Group Code CO on remittance advice and flag these amounts as non-collectable from patients.
04Establish a process to identify and refund any patient payments already collected for amounts reported with CARC 303, documenting the correction.
05Train billing staff and notify vendors that CARC 303 amounts are protected under QMB balance-billing protections and cannot be billed or collected.
If missed: Failure to comply will result in improper patient collection and potential regulatory violations of QMB protections.
Original notice
[California] Update: Unpaid Medicare cost share will be reported with CARC 303
providernews.anthem.com · Always check the source before changing claims.