A rejected claim is not a denied claim.

Two different answers

When a claim leaves your office, it passes two checkpoints before anyone decides whether to pay it. First the clearinghouse and the payer check that the file is built correctly. Then the payer checks each claim against its front-end edits: is this a member it knows, a provider it knows, a claim with every required field? A claim that fails either check is rejected. It never enters the payer’s claims system for a decision.

A claim that passes both checks is accepted for processing. Days or weeks later the payer adjudicates it: pays it, reduces it or refuses it. A claim the payer refuses after adjudication is denied.

The 999: did the file arrive intact?

Your claims travel as an X12 837 file. The first response is a 999 implementation acknowledgment, which reports whether the file itself follows the X12 rules for that transaction. It does not look at whether a patient is covered or a code is right. It answers one question: can this file be read?

A 999 comes back as accepted, accepted with errors or rejected. A rejected 999 usually means every claim in that file or transaction was refused, and the cause is almost always in how the file was built: software setup, a clearinghouse setting, a malformed field. One patient’s typo rarely causes it. When you see one, call your clearinghouse or software vendor the same day.

An accepted 999 does not mean your claims were accepted. It means the file was readable. The claim-by-claim answer comes next.

The 277CA: did each claim pass the front door?

The 277CA claim acknowledgment reports, claim by claim, whether each one passed the front-end edits and was accepted for processing, or was rejected. The clearinghouse sends one for its own edits, and the payer often sends another for its edits. A claim can pass the clearinghouse and still be rejected by the payer.

Front-end rejections in a chiropractic office tend to come from the same short list:

• The subscriber ID, name or date of birth does not match the payer’s member record. A new card, a married name or a dependent billed under the wrong subscriber will do it.
• The rendering or billing provider’s NPI is not on file with the payer, or not linked to the group.
• The payer ID is wrong, so the claim went to the wrong payer or the wrong plan.
• A required field is missing or malformed: a diagnosis pointer, a date, a billing address. The billing provider address must be a street address, not a post office box.

Every one of those is administrative. The fix belongs to whoever owns registration and claim entry in your office, not to your provider.

One Medicare exception: Medicare sometimes returns a claim as unprocessable on the remittance itself, with reason code CO-16 and remark code MA130. It looks like a denial, but Medicare treats it as never filed, and it carries no appeal rights. Correct it and send a new claim.

Why the difference matters: the clock

Every payer sets a filing deadline. Medicare allows 12 months from the date of service. Commercial contracts are often shorter, so check yours. A rejected claim was never accepted, so the payer has no record of receiving it on time. The deadline keeps running while the claim sits rejected in a report nobody opened.

The fix differs too. A rejected claim has nothing in the payer’s system to replace, so you correct it and send it as a new original claim. A denied claim already exists at the payer. Sending it again as a new claim usually earns a duplicate denial, reason code 18. Commercial payers generally take a corrected claim that replaces the original (claim frequency code 7), citing the payer’s claim control number from the remittance. Medicare Part B accepts only original claims, so a processed Medicare claim is fixed through a reopening or an appeal instead. The guide to chiropractic denial codes covers which route fits which denial.

Where rejected claims hide

A denial announces itself. It arrives on the remittance beside the claims that were paid, and someone posting payments will see it. A rejection arrives only in the clearinghouse’s acknowledgment reports. If nobody opens those reports, the claim stays marked as sent in your software indefinitely, looking like a claim the payer is still thinking about.

Three checks keep rejected claims from hiding:

1. Every business day, open the 999 and 277CA reports for every file sent the day before. Fix and resend each rejection the same day.
2. Every week, list claims sent more than a few days ago that have no acknowledgment at all. A claim with no 999 or 277CA may never have left.
3. Every week, list claims accepted more than 30 days ago with no remittance. Ask the payer for the claim’s status by electronic claim status inquiry, the 276/277, or on the payer’s portal.

Then, when the remittance does arrive, match its deposit and work its denials.

How Claims Native handles rejections

We check each claim against the payer’s rules before it goes out and fix what we can, so fewer claims come back rejected. We track every filing deadline and every claim that goes quiet. When a rejection needs a fact only your office has, such as a new insurance card, it comes to you once, with the claim and the payer’s exact words.

Sources

• CMS, Version 5010 acknowledgements: 999 and 277CA.
• X12, Claim Status Category Codes. Category A3: rejected and not entered into the adjudication system.
• Noridian JE Part B, Timely filing. A rejected claim does not enter the claims processing system.
• First Coast Service Options, Returned or rejected unprocessable claims and timely filing.
• CMS, Medicare Claims Processing Manual, Chapter 1, section 70: time limits for filing.
• CMS, Version 5010 national call. Billing provider street address; post office boxes go in the pay-to address.
• X12, Remittance Advice Remark Codes.