Denied or never billed: which fix an implant line needs

Appealing a denied ASC implant claim means using the payer’s own reconsideration and appeal process, inside the deadline in your contract. That process only reviews what was on the claim. An implant line that was left off the claim is not appealed at all: it is added with a corrected claim, and a corrected claim can run on the original filing deadline rather than on the appeal window.

Six questions about ASC implant billing covers denials and underpayments in a few paragraphs. This is the long version, read out of the rules and procedures that set each route: the X12 code lists a remittance is written in, the federal ERISA claims regulation, two commercial payers’ published procedures, the Medicare appeals regulations, and two workers’ compensation programs.

None of them governs your commercial contract, and one of the payers says so in as many words. They are useful because several of them draw the same line in different places, between asking a payer to look again and telling a payer something it was never told.

What does the denial code on an implant line tell you?

It tells you which of those two situations you are in, which is why the code comes before the appeal.

An electronic remittance explains each adjustment in two code sets that X12 maintains. Claim adjustment reason codes (CARCs) “describe why a claim or service line was paid differently than it was billed.” Remittance advice remark codes (RARCs) “provide additional explanation for an adjustment already described by a Claim Adjustment Reason Code (CARC) or convey information about remittance processing.”

The lists define what each code means. They do not say which code a given payer attaches to an implant line, so the table below is a reading aid rather than a prediction: nine codes whose published descriptions fit the ways an implant line fails, with X12’s wording in the middle column and our reading in the last.

Nine remittance codes, in X12’s words and ours

Code	X12 description	Our reading for an implant line
CARC 16	“Claim/service lacks information or has submission/billing error(s).”	Something on the claim itself is missing or wrong. The remark code beside it says what.
CARC 252	“An attachment/other documentation is required to adjudicate this claim/service.”	The payer wants a document. The remark code names it.
RARC M23	“Missing invoice.”	The document is the vendor invoice.
RARC N354	“Incomplete/invalid invoice.”	An invoice arrived and did not satisfy the payer.
RARC M29	“Missing operative note/report.”	The document is the operative note.
CARC 97	“The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated.”	The payer treated the implant as part of the procedure payment.
CARC 234	“This procedure is not paid separately.”	The same outcome as 97, stated as a rule rather than as a bundle.
CARC 45	“Charge exceeds fee schedule/maximum allowable or contracted/legislated fee arrangement.”	The line was reduced to an allowed amount. The code does not say what the contract’s amount should have been.
CARC 29	“The time limit for filing has expired.”	The line arrived after the filing deadline.

Three things in that table are worth slowing down for.

First, codes 16 and 252 look alike and are not. Code 16’s own usage note reads “Do not use this code for claims attachment(s)/other documentation,” and both codes require a remark code alongside them. Read together, 16 points at the claim form and 252 points at a document. They are fixed by different routes, as the payer sections below show.

Second, codes 97 and 234 are not documentation problems, and sending an invoice does not answer them. On our reading they are a statement about how the payer reads your contract. Whether the implant should have been paid separately is the subject of what an ASC implant carve-out has to define.

Third, code 45 appears on a line that was paid. Read literally, it says the charge was above the contracted amount. It does not state the contracted amount, so the code alone cannot tell a correctly paid implant line from one paid below the contract. That is our reading of the description, and it is why an underpaid line has to be found by comparing the payment with the contract rather than by reading codes.

Is a provider’s appeal the same as the patient’s ERISA appeal?

Not when the dispute is a contract matter, according to the Department of Labor, and the difference decides which deadline you are on.

One appeal deadline is written into federal regulation, and it is 180 days. It comes from 29 CFR 2560.503-1, the Department of Labor’s claims procedure regulation for plans covered by ERISA, which requires a group health plan’s procedures to “provide claimants at least 180 days following receipt of a notification of an adverse benefit determination within which to appeal the determination.” The definition of an adverse benefit determination is broad enough to reach a short payment: it includes “a failure to provide or make payment (in whole or in part) for, a benefit.”

The word that matters is claimants. The regulation sets “minimum requirements for employee benefit plan procedures pertaining to claims for benefits by participants and beneficiaries (hereinafter referred to as claimants).” The right belongs to the patient.

The Department’s own FAQ on the regulation addresses providers directly, in two answers.

• Contract disputes are outside it. Asked whether the group health plan requirements apply to contractual disputes between providers and insurers, the Department answers “No, provided that the contractual dispute will have no effect on a claimant’s right to benefits under a plan.” The regulation does not apply to “requests by health care providers for payments due them” under “contractual arrangements between the provider and an insurer or managed care organization, where the provider has no recourse against the claimant for amounts, in whole or in part, not paid by the insurer or managed care organization.” Where the provider does keep recourse against the patient, the FAQ says the request “would constitute a claim for benefits by the claimant.”
• An assignment of benefits is not an authorization to appeal. Asked whether an assignment designates the provider as an authorized representative, the Department answers “No. An assignment of benefits by a claimant is generally limited to assignment of the claimant’s right to receive a benefit payment under the terms of the plan. Typically, assignments are not a grant of authority to act on a claimant’s behalf in pursuing and appealing a benefit determination under a plan.”

Put those together for a network ASC whose contract bars it from billing the patient for the unpaid amount. We read the FAQ to mean that center’s dispute over an implant line is a contract matter, on the contract’s deadline, and that the 180 days is not a floor it can rely on. That is our reading of agency guidance, not legal advice, and an out-of-network center or one acting as a patient’s authorized representative is in a different position.

Corrected claim vs appeal: what do commercial payers ask for?

Two published procedures, which is two payers rather than the market. Both separate the routes explicitly, and both put the missed line on the corrected claim.

UnitedHealthcare. Its 2026 Care Provider Administrative Guide, effective April 1, 2026 for its commercial and Medicare Advantage networks, describes a two-step process: “First, submit a claim reconsideration request. If you don’t agree with the outcome of the reconsideration, you may submit an appeal.” The window covers both steps together: “You must submit your reconsideration and appeal to us within 12 months from the date of the original claim EOB or PRA (or as required by law or your Agreement).”

The process is for one kind of problem. It is “for when you disagree with the payment or denial of an individual claim,” and a reconsideration request should include “any necessary additional supporting materials not included in the original claim submissions.” On our reading, a denial for a missing document and a line you believe was paid short both fit that description.

A line that was never billed does not. The guide’s corrected claim section is direct about it:

• “If services were missed or incorrect on your initial submission, please do not submit a second original claim as it may reject, deny or generate incorrect claim payments. Please submit a corrected (replacement) claim using the appropriate frequency code along with the claim number you are replacing.”
• Its examples of a corrected claim begin with a claim that has “Additional services omitted from the initial claim.”
• “A corrected claim is not a request for reconsideration.”
• “Corrected claims will fully replace any prior submission so please ensure the corrected claim is comprehensive of the services you would like to be considered for payment.”

Then the deadline, which is not the 12 months. “Your Agreement requires that all information necessary to process a claim must be received by UnitedHealthcare within a specified number of days from the date of service, date of discharge or last date of service on an outpatient claim. This number of days also applies to submission of corrected claims.” The guide’s own illustration uses a last date of service of May 1 and a 90-day limit, in which case everything, “including any corrections, must be received by UnitedHealthcare no later than 90 days after May 1.” The 90 days is the guide’s example. Your limit is the one in your agreement.

One more sentence in that guide is worth knowing if the same implant keeps paying short. The single claim process “will not resolve contract configuration errors,” and the guide sends those to a claim research project or a provider advocate instead.

Blue Cross and Blue Shield of New Mexico. A provider notice dated April 1, 2024 says that from July 1, 2024 “all late charges must be submitted to Blue Cross and Blue Shield of New Mexico as a corrected claim after the original claim has been processed,” and defines them: “Late charges, or additional charges, represent changes for items and services that were submitted after the bill was created and not included in the original bill.” The instructions, which the notice gives for commercial members, are specific.

• “The entire claim should be resubmitted with frequency code 7 (replacement of prior claim). Do not submit a corrected claim using frequency code 5 (late charges). If the corrected claim is submitted using frequency code 5 this could result in a denial of the claim.”
• “The corrected claim should include all line items previously processed correctly. Reimbursement for line items no longer included on the corrected claim may be subject to recoupment by BCBSNM.”

The plan’s guide to claim frequency codes says the same thing in one line: “If a charge was left off the original claim, submit the additional charge with all of the previous charges as a replacement claim using frequency code 7.” It also requires the original claim number on the replacement, without which “adjustment requests will generate a compliance error and the claim will reject.” Neither document states a number of days.

Notice what the recoupment sentence means in practice. A corrected claim that adds the implant and leaves off a line that was already paid can put that payment at risk. The replacement has to be the whole claim, correct.

What do the Medicare rules add?

Not many implant disputes, because Medicare packages most implants into the procedure payment, as what the CMS manual actually says about ASC implant billing covers. What the Medicare regulations add is the cleanest statement of the same distinction, written into federal rule.

An appeal starts with a redetermination, and 42 CFR 405.942 sets the window: “any request for redetermination must be filed within 120 calendar days from the date a party receives the notice of the initial determination,” subject to an extension for good cause.

An error or an omission goes somewhere else. 42 CFR 405.927: “Minor errors or omissions in an initial determination must be corrected only through the contractor’s reopenings process.” Section 405.980 then requires the contractor to “process clerical errors (which includes minor errors and omissions) as reopenings, instead of as redeterminations,” and gives mathematical or computational mistakes, inaccurate data entry and denials of claims as duplicates as examples. A party may ask for a reopening “within 1 year from the date of the initial determination or redetermination for any reason,” with longer periods for good cause and for correcting a clerical error. The contractor decides whether something is a clerical error, and if it disagrees it must dismiss the request and advise the party of any appeal rights, provided the time to appeal has not expired.

The claim itself has its own deadline. Under 42 CFR 424.44, for services furnished on or after January 1, 2010, it “must be filed no later than the close of the period ending 1 calendar year after the date of service,” with listed exceptions.

So Medicare has three clocks. One starts when the contractor answers, one starts at the initial determination, and one starts on the date of service.

What do workers’ comp rules allow?

Two programs, read from their regulations. The deadlines here are shorter, and one of them says outright that a reconsideration cannot change what was billed.

Texas. Under 28 Tex. Admin. Code section 133.20, a health care provider “must not submit a medical bill later than the 95th day after the date the services are provided,” with statutory exceptions. If the provider is dissatisfied with the carrier’s final action, section 133.250 lets it ask the carrier to reconsider, and “the health care provider shall submit the request for reconsideration no later than 10 months from the date of service.”

A written request has four required contents. The first is that it shall “reference the original bill and include the same billing codes, date(s) of service, and dollar amounts as the original bill.” It must also include the original explanation of benefits if received, “any necessary and related documentation not submitted with the original medical bill,” and “a bill-specific, substantive explanation” that “provides a rational basis to modify the previous denial or payment.” The carrier then has 30 days from receiving the request to take final action.

A provider still dissatisfied can take a fee dispute to the Division of Workers’ Compensation. Under section 133.307 the request “shall be filed no later than one year after the date(s) of service in dispute,” with exceptions for related disputes, and a requestor must file on time “or waive the right” to that process.

Read the first required content again. The same billing codes and the same dollar amounts means, on our reading, that a Texas reconsideration cannot introduce an implant line the original bill did not carry. We read a line that was never billed as a bill not yet submitted, which would put it on the 95-day clock rather than the 10-month one. The Texas implant rules themselves, including the signed certification of actual cost, are in what an implant claim needs behind it.

Federal, through OWCP. 20 CFR 10.812 gives a provider “whose charge for service is only partially paid because it exceeds a maximum allowable amount set by the Director” the right to request reconsideration of the fee determination “within 30 days.” The request must come with documentary evidence of one of three things: “that the procedure performed was incorrectly identified by the original code, that the presence of a severe or concomitant medical condition made treatment especially difficult, or that the provider possessed unusual qualifications.” The section adds: “These are the only three circumstances which will justify reevaluation of the paid amount.” If the district office still disallows the amount, the provider has 30 days from that decision to apply to the Regional Director, whose decision is final.

None of the three circumstances is about what a device cost. That is the text of the section, and it covers only reductions to a maximum allowable amount.

Every route, side by side

Each route, from an appeal to a frequency code 7 corrected claim, and what its deadline is counted from

Route	What it is for	Window	Counted from
ERISA group health plan appeal	A claimant’s adverse benefit determination, which includes a payment made in part	At least 180 days	Receipt of the notification
UnitedHealthcare reconsideration and appeal	Disagreeing with the payment or denial of an individual claim	12 months for both steps, or as required by law or your Agreement	The date of the original claim EOB or PRA
UnitedHealthcare corrected claim	Services missed or incorrect on the initial submission	The timely filing limit in your Agreement	The date of service, or the last date of service on an outpatient claim
BCBS of New Mexico corrected claim	Late or additional charges, and any charge left off the original claim	Not stated in the two documents cited	Not stated in the two documents cited
Medicare redetermination	Appealing an initial determination	120 calendar days	Receipt of the notice of the initial determination
Medicare reopening	Minor errors or omissions, and clerical errors	1 year for any reason, longer in listed cases	The date of the initial determination or redetermination
Texas workers’ comp reconsideration	Dissatisfaction with the carrier’s final action, on the same codes and amounts as the original bill	10 months	The date of service
Texas workers’ comp fee dispute	Dissatisfaction after reconsideration	One year, with exceptions	The date(s) of service in dispute
OWCP fee reconsideration	A charge partially paid because it exceeds a maximum allowable amount	30 days	Not stated in the section

Why the missed implant line runs on the shortest clock

Look down the last column. In the commercial and Medicare rows, the routes for disagreeing with a payer are counted from the payer’s answer: the explanation of benefits, the notice, the determination. The routes for telling a payer something new are counted from the date of service. Texas counts all of its deadlines from the date of service, and gives the bill itself the shortest of them.

That is a sensible design. An appeal asks a payer to look again at something it was shown, and an implant line that never reached the claim was never shown to it. There is no denial to appeal, no reason code to read and no notice to start a clock. A denied line produces all three.

So the two kinds of implant problem age differently. A denied line arrives in a work queue with a code on it and a deadline that begins on the day the payer answered. A line that was never created produces no remittance entry at all, and under the rules above its only deadline began on the date of service. The vendor invoice that would show the line is missing can arrive after the claim has gone, which is the sequence where implant charges fall out walks through. The denied line gets a clock that starts when the payer answers, and the missing line has been on the clock since the date of service.

None of this is a statement about anyone’s diligence. A denial queue is built to work what payers send back, and it does. The clinical record, the billing system and accounts payable each hold their own fact about the implant, and none of the three is built to check the other two, so a line absent from the claim is absent from the queue as well.

A working order for an implant line that did not pay

Drawn from the sources above, with the last item marked as ours because none of them asks for it.

1. Read the reason code and the remark code before choosing a route. A claim error, a missing document, a bundling decision and a late filing are four different problems.
2. Decide which of three things happened: the line was denied, the line was paid below the contract, or the line was never on the claim.
3. For a denied line, use the payer’s reconsideration or appeal process and send what the remark code names, with the materials that were not in the original submission.
4. For a line paid below the contract, use the same process and say specifically why the payment is not what the contract provides. If the same shortfall repeats across claims, ask whether it is a contract set-up problem rather than a claim problem.
5. For a line that was never on the claim, send a corrected claim: the whole claim, as a replacement under frequency code 7 at both payers read here, with the original claim number. Not a second original claim, and not a reconsideration request.
6. Take every deadline from your own agreement. UnitedHealthcare’s guide says so itself: “If there is inconsistency between the terms of your Agreement and this guide, your Agreement controls.”
7. Ours, not theirs: compare the implants on each month’s vendor invoices with the claims that went out, while the filing limit is still open. It is the only item on this list that finds a line no remittance will ever mention.

Where Bill-Back fits

Item seven is the whole product, so treat this section as the vendor pitch it is.

Bill-Back reads three documents a center already has: the monthly case log export from the PMS, the vendor invoice PDFs, and the Paid Claims Report, which shows which implant lines were already billed. Your file is read in your browser, and only what the audit needs is sent: procedure month, payer, CPT code, procedure description, surgeon name, and supply notes, plus a hashed case reference if you map one. Supply notes are sent as the nurse wrote them, because the device description and catalog number are what the audit matches on. Everything sent is handled under a signed BAA.

Each supply note is matched to a vendor catalog number and priced at your contracted rate. Then someone on your side clears anything already on a claim, which is the step that separates matched value from recoverable dollars. What survives becomes a payer-ready Recoup Packet: the corrected claim, the reimbursement basis quoted from your own contract, and the matched invoice line as Exhibit A, for your own biller to submit. A corrected claim inside the filing window, not an appeal.

Bill-Back does not work your denials. Your biller or RCM partner already does, and nothing above changes that. It works the lines that never became one.

Commercial payers only, for the reason in the Medicare section. Stryker and Arthrex invoices are supported today, everything else goes through manual review, and new invoice layouts are added as centers send their invoices. Free to audit, and you only pay when the payer pays.

You can estimate what that seam is worth at your case volume in about thirty seconds, or start a free audit against a month of your own files.

Sources

Every rule and procedure above traces to one of these.

Code lists

• Claim Adjustment Reason Codes, X12. Codes 16, 29, 45, 97, 234 and 252.
• Remittance Advice Remark Codes, X12. Codes M23, M29 and N354.

Government and regulatory

• 29 CFR 2560.503-1, Claims procedure, U.S. Department of Labor, via eCFR. Paragraphs (a), (h)(3)(i) and (m)(4).
• Benefit Claims Procedure Regulation FAQs, Employee Benefits Security Administration, U.S. Department of Labor. Questions A-8 and B-2.
• 42 CFR 405.927, 405.942 and 405.980, Medicare initial determinations, redeterminations and reopenings, via eCFR.
• 42 CFR 424.44, Time limits for filing claims, via eCFR.
• 20 CFR 10.812, Office of Workers’ Compensation Programs, U.S. Department of Labor, via eCFR.
• 28 Tex. Admin. Code section 133.20, Medical Bill Submission by Health Care Provider, via Cornell LII.
• 28 Tex. Admin. Code section 133.250, Reconsideration for Payment of Medical Bills, via Cornell LII.
• 28 Tex. Admin. Code section 133.307, MDR of Fee Disputes, via Cornell LII.

Payer procedures

• 2026 UnitedHealthcare Care Provider Administrative Guide for Commercial, Individual Exchange and Medicare Advantage, effective April 1, 2026. Chapter 10, the corrected claim sections and the claim reconsideration and appeals process.
• Late and Added Charges Must Be Submitted as a Corrected Claim, Blue Cross and Blue Shield of New Mexico provider notice, April 1, 2024.
• Electronic Replacement/Corrected Claim Submissions, Blue Cross and Blue Shield of New Mexico.