Guides
Billing and denials, explained plainly
Evergreen guidance on NCCI edits, medically unlikely edits and reading a remittance, for working medical billers. Where a claim depends on the specific code pair or payer, we link the cited lookup page rather than stating a number that might not be yours.
CO-29 denial code: the time limit for filing has expired
CO-29 means the claim missed its filing deadline, and no amount of clinical documentation will overturn it on the merits. Here is when it is genuinely worth appealing, and how to stop it recurring.
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Denial management software vs. outsourcing: what actually fixes the number
Percentage-fee outsourcing or flat-fee software? Compare the real economics, then scrub a claim free.
Best claim scrubbing software in 2026: what matters
Most claim scrubber comparisons rank by feature checklist. Here is what actually separates a scrubber worth trusting from one that just adds a step, and where our own tool sits honestly against that bar.
Why claim denial rates are rising in 2026
Denial rates are not just a perception problem. Recent AHA and Experian Health data show why more claims are denying, why appeals are underused despite high overturn rates, and what that means for billing offices right now.
How to write a medical claim appeal letter (template)
A working template for a medical claim appeal letter, section by section, with the placeholders filled in from a real denial so you can see exactly what a reviewer needs to see.
Timely filing limits by payer: 2026 quick reference
Timely filing limits vary widely by payer, and several payers publish no single national default at all. Here is what we can confirm, what we cannot, and why guessing at a deadline is worse than checking.
CARC vs RARC: what the difference actually means
A claim adjustment reason code and a remittance advice remark code answer different questions on the same remittance. Here is what each one is for, and why you need both to actually fix a denial.
Modifier 25 vs 59: which one actually applies?
Modifier 25 and modifier 59 solve two different bundling problems and are not interchangeable. Here is how to tell which one your claim actually needs, with a worked example of each.
PR-204 denial code: non-covered services and ABNs
PR-204 means the service is excluded from the plan entirely, not denied for lack of medical necessity. Here is how to confirm the exclusion, when an ABN changes the outcome, and when to bill the patient.
CO-45 denial code: write-off or a real appeal?
CO-45 usually means a routine contractual write-off, not an error. Here is the narrow set of circumstances where it is actually worth disputing, and why appealing the rest just wastes a filing window.
CO-97 denial code: is a bundling denial appealable?
CO-97 means a service is bundled into another procedure already paid on the claim. Sometimes that is correct and sometimes it is a missing modifier. Here is how to tell the difference before you appeal.
CO-16 denial code: fixing missing information fast
CO-16 means the claim lacks information or has a submission error, and it always arrives with a remark code that names the actual problem. Here is how to read the pair and resubmit correctly the first time.
Writing a claim reconsideration request that a payer actually has to answer
What separates a reconsideration request that gets overturned from one that gets binned, deadlines by payer, and a worked example. Scrub your claim free.
Reading a remittance: turning a CARC and RARC pair into a corrective action
A remittance advice gives you a CARC and usually one or more RARCs. Here is what each one is actually telling you, how the group code decides who owes the money, and how to turn the pair into a ranked next step instead of a guess.
MUE MAI 1 vs 2 vs 3: which unit-count denials you can actually appeal
A medically unlikely edit denial is not one thing. The adjudication indicator, MAI 1, 2 or 3, decides whether reducing units, resubmitting with documentation or appealing is even possible. Getting this wrong wastes an appeal on a code that can never win one.
How NCCI PTP modifier indicators work, and when modifier 59 is actually legitimate
NCCI procedure-to-procedure edits carry a modifier indicator of 0, 1 or 9. Only indicator 1 can ever be bypassed by a modifier, and only when the two services were genuinely distinct. Here is how the check actually works.
A guide explains the mechanism. Your remittance decides the code.
Look up the exact CARC, RARC or modifier on your claim, cited to the X12 or CMS source, or scrub the claim before you send it.