OA-B4: Late Filing Penalty

What Does OA-B4 Mean?

OA-B4 is uncommon and typically appears when the late filing penalty calculation involves coordination between payers or special filing circumstances. This may occur when the timely filing deadline was affected by a prior payer's delayed adjudication in a COB scenario.

When CARC B4 appears on a remittance, the payer is applying a financial penalty because the claim was submitted after their specified filing deadline. Timely filing requirements vary by payer — Medicare allows one year from the date of service, most commercial payers require 90 to 180 days, and some Medicaid programs have even shorter windows. Missing the deadline can result in either a partial payment reduction (penalty) or a full denial with no payment.

The late filing penalty is one of the most preventable denials in revenue cycle management, yet it remains common because of the complexity of tracking different deadlines across dozens of payers. The penalty also applies to corrected claims and resubmissions — the clock does not reset when you resubmit a denied claim, so delays in working denials can push corrected claims past the filing window.

CARC B4 is disputable if you can prove the claim was submitted on time. Clearinghouse confirmation reports, electronic acknowledgment timestamps, and payer portal submission records all serve as evidence of timely filing. If a system outage, clearinghouse failure, or other technical issue prevented submission, documenting the issue contemporaneously strengthens your case for a timely filing exception.

How to Resolve

Determine whether the claim was genuinely filed late, gather proof of timely submission if available, and dispute or absorb the penalty accordingly.

1. Check COB adjudication dates If this is a secondary claim, verify whether the primary payer's delayed adjudication caused the secondary claim to miss the filing deadline. Many payers reset the timely filing clock based on the primary payer's remittance date.
2. Dispute with supporting documentation If the primary payer's delay caused the late filing, submit the primary payer's remittance with dates to demonstrate the filing timeline was reasonable given the COB sequence.

Common RARC Pairings

The RARC code tells you exactly what triggered the OA-B4:

How to Prevent OA-B4

• Track primary payer adjudication dates and submit secondary claims immediately upon receiving the primary remittance
• Understand each secondary payer's timely filing rules — some measure from the date of service, others from the primary payer's adjudication date

Also Filed As

The same CARC B4 may appear with different Group Codes:

Related Denial Codes