Short, specific notes on how insurers actually pay independent practices, and how to check your own numbers.
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The reason code says what the payer did; the remark code says why. A working table of the RARCs specialty practices see most, from N130 and N381 to M15, N290 and MA130, with the usual CARC pairing and the fix for each.
When a payer pays your E/M visit a level down. The remittance signals, four questions that separate a payer downcode from a coding error, what MDM or time must show under the 2021 rules, and how to request reconsideration.
Non-contracted providers are generally owed what original Medicare would pay; contracted providers are owed the contract. How to tell which applies, Florida's three payment localities, the 835 check, and where each dispute goes.
Original analysis of Florida's state claim dispute program records: providers paid in 89% of decided cases, a third closed by plan opt-outs, and results that vary sharply by health plan.
Denial code CO-11 means the payer's edit says the diagnosis on the claim doesn't support the procedure. Usually a linkage or specificity error, sometimes a coverage policy in disguise. How to tell, and what to resubmit.
Denial code CO-15 means an authorization exists but the number on the claim is missing, wrong, or doesn't cover this service, date, or provider. Almost always a matching problem, and almost always recoverable.
OA-23 is not a denial. It's the secondary payer accounting for what the primary already paid and adjusted. The code is where coordination-of-benefits math goes wrong, and where secondary underpayments hide.
Denial code CO-27 means the payer says the patient's coverage ended before the service. Sometimes true. Often a retroactive termination, a plan change, or a COBRA gap. The three checks, the patient conversation, and Florida's one-year limit on retroactive denials.
Denial code CO-59 means the payer reduced a line under multiple or concurrent procedure rules. Not a denial; a formula. The formula is often applied wrong: misranked procedures, add-ons reduced, bilateral counted twice. How to recompute it.
Denial code CO-119 means the payer says the patient hit a visit, unit, or dollar limit for the period. The count is often wrong: visits from another provider, a period that reset, a cap that doesn't apply. What to check, and when the patient can be billed.
Denial code CO-151 means the payer says the documentation doesn't support this many units or this frequency. Usually a medically unlikely edit or a frequency policy. Which ones reverse with the record, which need a modifier, and which are real limits.
Denial codes CO-170 and CO-171 mean the payer won't pay this service when billed by this provider type, or by this provider type in this setting. Usually a PA or NP billing question, a credentialing gap, or a supervision rule. What reverses it.
Denial code CO-204 means the payer says the plan doesn't cover this service, equipment, or drug at all. Sometimes true. Often a benefit-loading error, a wrong code, or a CO that should have been PR. The checks, and the patient conversation.
Denial codes CO-231 and CO-234 are the other two bundling codes next to CO-97 and CO-236. Mutually exclusive means the payer says two procedures can't both have happened; not paid separately means the payer folded one into another. Which reverse with a modifier, and which don't.
Reference. The 175/210% rates, the three-day and ten-day authorization rules, the carrier's 45-day clock, all 57 EOBR codes, and the DFS petition step by step, quoted from the statute, the rules, the manual, and the forms.
Reference. The three-part manual and the appeal forms in one place: 180-day filing, corrected-claim rules, the one-year appeal and which form goes where, offset recovery, authorization by product, the 2026 ASC groups, and nine places the manual contradicts itself.
Reference. Sections 627.6131 and 641.3155 quoted: the 20/90/120-day clocks, 12 percent interest, the 12-month underpayment window, the recoupment limit and offset bar, and when an authorization binds the payer.
The six kinds of medical billing denials, how often each happens, what causes it, and which ones reverse with a document or a corrected claim. Benchmarks from Premier and Experian, and a triage order.
Four provider-side appeal letter templates: timely filing with proof, authorization on file, underpayment against contract, and medical necessity with the note. What each must contain, and where to send it.
For Florida providers: what each EOBR code means, which denials are worth a petition, the three-business-day rule that makes carrier silence consent, and the traps that get petitions dismissed.
How a Medicare Part B denial is appealed: redetermination in 120 days, reconsideration in 180, then the ALJ. Why timely-filing denials can't be appealed, how reopenings work, and how Medicare Advantage differs.
An in-network practice paid at out-of-network rates or denied outright is usually a loading error: wrong NPI, tax ID, location, or an effective date the payer never entered. How to find it, fix it, and reprocess the batch.
When an insurer demands money back, it has to follow rules. Florida bars overpayment recoupment after 12 months on state-regulated plans, requires notice, and gives you the right to contest. What to check before you refund, and how offsets hide in the 835.
A plain-language table of the denial codes that matter most to independent practices: what each CARC means, what it usually is in practice, and which ones are recoverable. With the deeper note for each.
Denial code CO-4 means the procedure code and modifier don't agree, or a required modifier is absent. What triggers it in surgical and office claims, the fix, and when it's really a payer edit.
Denial code 18 means the payer thinks it already has this claim. Often true. Sometimes it's two legitimate services on one day that the payer collapsed. How to tell, and what to send.
Denial code CO-22 means the payer thinks someone else pays first. The claim isn't lost, it's parked. What the payer needs, the 90-day secondary window in Florida, and the auto accident and work injury cases.
Denial code CO-50 says the payer doesn't consider the service medically necessary. Some are clinical disputes. Many are a diagnosis code that didn't match a coverage policy. How to tell, and where the line is.
Denial code CO-96 says the charge isn't covered, and on its own says nothing about why. The remark code does. The five reasons it fires, which ones reverse, and the patient-billing rules that follow.
Denial code CO-109 means this payer isn't the one that owes. Medicare Advantage instead of Medicare, a carve-out vendor, a TPA, workers' comp. How to find the right payer fast, before the real one's window closes.
Denial code CO-236 means the payer's NCCI edit blocked a procedure pair on the same day. Some pairs are truly bundled. Many allow a modifier the claim didn't carry. How to read the edit table and what to send.
Denial code CO-252 means the payer won't adjudicate without a document: op note, invoice, records. It's a request, not a decision. What they want by remark code, how to send it, and the deadline that runs while you wait.
Insurers now downgrade level 4 and 5 visits by algorithm before paying. How to spot it in your remittances, what the Maryland order changed, and how to get the difference back.
A claim paid below contract still posts to a zero balance. No alert fires. Here is why that happens, what a zero-balance review is, and how to run one without new software.
An underpayment appeal is arithmetic plus a contract page. What to pull, what to write, where to send it, the deadlines that apply, and why you should file by pattern instead of by claim.
The electronic remittance carries the billed code, the paid code, the allowed amount, every adjustment reason, and the provider-level offsets. Most of it never reaches your reports. Here is what to read.
Denial recovery is getting paid on claims an insurer denied for a fixable reason. Which denials qualify, why billing teams can't work them at scale, what recovery costs, and the deadlines.
We read every Florida OIR compliance report from 2023 through mid-2026. What the enforcement record covers, and the remedies your practice uses to recover an underpayment itself.
The vendors that reprice and edit medical claims earn a percentage of what they cut. The fee model is documented in their own SEC filings, a granted patent, and a public trial record.
Authorization and payment are two separate gates. The gap in the payers' own numbers, the federal rule that makes an MA approval binding, and Florida's 120-day tripwire.
Denial and appeal-overturn rates at UHC, Humana, Aetna and Florida Blue, extracted from their first-ever CMS-0057 disclosures, with the Florida slices and the appeal gap they reveal.
Florida law gives providers a non-waivable 12-month window to claim underpayments from insurers and HMOs, with 12% interest. Most practices never use it.
The 20-, 90-, and 120-day clocks Florida puts on insurers and HMOs, the 12% interest on overdue claims, and how an independent practice can use them.
SB 362 raised Florida workers' comp rates effective 2025. Slow-loaded carrier rates, the 60-day EOBR petition clock, and how any specialty treating work injuries can check.
Appeal windows at Florida Blue, UHC, Aetna, Cigna, Humana and Medicare: a working table with honest confidence caveats and the 12-month statutory backstop.
Do nothing, work it in-house, buy software, or hire a contingency firm. An honest comparison of the four options, and the questions to ask any vendor.
The routine contractual adjustment is exactly where underpayment hides. How to recompute it against your contract, and when to let it go.
One code, two denials: the global-period branch and the bundling-edit branch. The date math, the modifier arsenal, and when no appeal exists.
An auth that exists, an emergency exception, or an elective miss. Three different problems wearing one code, with three different plays.
The proof hierarchy that overturns a timely-filing denial, why Medicare's version can't be appealed at all, and when the honest answer is to let it go.
The code tells you nothing by design. The remark code carries the reason. RARC routing, resubmission mechanics, and why a letter is the wrong tool.
The group code, not the denial code, decides who can be billed. CO is never patient money, PR usually is, and QMB patients can't be billed at all.
The afternoon check: pull your zero-balance claims, compare allowed amounts against contracted rates, and read the three patterns that reveal systematic underpayment.