Resources
Tools, references and primary sources
Everything on this page is free and requires no contact details. The second half is a directory of sources we do not control — because a billing claim you cannot verify is worth less than no claim at all.
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Revenue Leak Calculator
Enter monthly claim volume, average claim value and denial rate. Returns annualised revenue lost, benchmarked against published MGMA, Premier and Optum figures.
Denial Code Lookup
CARC and RARC codes in plain English, each with what caused it, how to fix it, and how to stop it recurring.
How to Choose a Medical Billing Company
A buyer's guide: five provider models and who each suits, the numbers to demand before discussing rate, contract terms that matter more than price, and seven red flags.
RCM Benchmarks
Current denial, AR and cost-to-collect benchmarks — every figure traceable to a named publisher, dataset and year, plus the widely-quoted figures we refuse to use and why.
Medical Billing Glossary
Definitions for claims, coding, denial, financial and compliance terminology, written around the distinctions that actually change what you do.
Comparisons
In-house vs outsourced, percentage vs flat fee, offshore vs domestic, software vs service — each naming the case where the answer is not us.
Blog
Longer-form writing on denial reduction, coding changes and revenue cycle operations.
Primary sources
Where the rules actually come from
43 authoritative references, none of them ours.
Why we link out
Rules and regulation
The federal sources that actually govern how a claim must be submitted, adjudicated and appealed.
- Medicare Claims Processing Manual (opens in a new tab)
Centers for Medicare & Medicaid Services
The operative manual for how Medicare claims must be coded, submitted, adjusted and appealed. When a payer policy and a vendor's advice disagree, this settles it.
- CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F) (opens in a new tab)
Centers for Medicare & Medicaid Services
The rule imposing prior authorization decision timelines and API requirements on impacted payers. It is the single largest scheduled change to authorization workflow this decade.
- No Surprises Act guidance (opens in a new tab)
Centers for Medicare & Medicaid Services
Balance billing restrictions, good faith estimates and the independent dispute resolution process — all of which change what a practice may bill a patient.
- Medicare Physician Fee Schedule lookup (opens in a new tab)
Centers for Medicare & Medicaid Services
Official allowed amounts by CPT/HCPCS code and locality. The reference point most commercial contracts are written against as a percentage.
- Global Surgery booklet (opens in a new tab)
Centers for Medicare & Medicaid Services
What the 10 and 90-day global periods include, and which modifiers break out of them. The authority behind most postoperative bundling disputes.
- Medicare claims appeals process (opens in a new tab)
Centers for Medicare & Medicaid Services
The five levels of appeal, what each requires and the deadline for each. Missing a level's deadline ends the appeal regardless of the claim's merits.
- Advance Beneficiary Notice of Noncoverage (ABN) (opens in a new tab)
Centers for Medicare & Medicaid Services
The form and the rules for issuing it. Whether a non-covered service can be billed to the patient usually turns on whether a valid ABN was obtained beforehand.
- Medicare timely filing requirements (opens in a new tab)
Centers for Medicare & Medicaid Services
The one-year filing limit and the narrow exceptions to it. Commercial payers set their own, usually shorter, limits by contract.
Code sets and claim standards
The maintainers of CPT, ICD-10-CM, HCPCS, CARC/RARC and the claim forms themselves.
- Claim Adjustment Reason Codes (CARC) (opens in a new tab)
X12
The authoritative, maintained CARC list. Our denial code lookup explains these in plain English; X12 is where the canonical definitions live.
- Remittance Advice Remark Codes (RARC) (opens in a new tab)
X12
The remark codes that qualify a CARC on an ERA. Reading the RARC is usually what tells you whether a denial is appealable.
- CPT code set (opens in a new tab)
American Medical Association
Maintainer of CPT. Annual changes to CPT are the most common cause of a sudden, unexplained rise in denials each January.
- ICD-10-CM official guidelines and files (opens in a new tab)
CDC / National Center for Health Statistics
The official ICD-10-CM code files and coding guidelines, updated annually. Specificity requirements here drive a large share of medical necessity denials.
- HCPCS Level II code set (opens in a new tab)
Centers for Medicare & Medicaid Services
Codes for supplies, drugs, DME and services outside CPT — and the modifier definitions that go with them.
- National Correct Coding Initiative (NCCI) edits (opens in a new tab)
Centers for Medicare & Medicaid Services
The procedure-to-procedure and medically-unlikely edits behind most bundling denials. Checking these before submission prevents the denial entirely.
- CMS-1500 claim form standards (opens in a new tab)
National Uniform Claim Committee
Maintainer of the CMS-1500 professional claim form and its data element definitions, plus the provider taxonomy code set.
- NCCI Policy Manual for Medicare Services (opens in a new tab)
Centers for Medicare & Medicaid Services
The reasoning behind the edits, chapter by chapter. Where the edit files tell you two codes conflict, this explains why — which is what an appeal has to address.
- Medically Unlikely Edits (MUE) tables (opens in a new tab)
Centers for Medicare & Medicaid Services
The maximum units of a code payable for one patient on one day. Unit-based denials usually trace to this table rather than to a coding error.
- Place of Service code set (opens in a new tab)
Centers for Medicare & Medicaid Services
The two-digit codes and their definitions. Place of service drives the facility versus non-facility payment rate, so an error here changes the amount paid, not just the acceptance.
- Evaluation and Management services guide (opens in a new tab)
Centers for Medicare & Medicaid Services
How E/M level is determined under the current medical decision making and time rules. The reference for any dispute about whether documentation supports a level.
Industry data and benchmarks
Publishers of the denial, AR and cost-to-collect figures quoted across this site.
- Revenue Cycle Denials Index (opens in a new tab)
Optum
Denial rates and denial causes derived from roughly 124 million hospital claim remits. Source of the avoidability and front-end origination figures used across this site.
- MGMA DataDive and MGMA Stat (opens in a new tab)
Medical Group Management Association
The practice-level operations benchmarks — days in AR, denial rate, cost to collect — that physician groups are actually measured against.
- MAP Keys revenue cycle metrics (opens in a new tab)
Healthcare Financial Management Association
Standard definitions for revenue cycle KPIs. Worth reading precisely because HFMA defines the metrics without publishing public target values — a distinction most vendor marketing ignores.
- CAQH Index: cost of administrative transactions (opens in a new tab)
CAQH
Per-transaction cost of eligibility checks, claim status inquiries and prior authorization, manual versus electronic. The best public evidence for automating front-end work.
- Claims denials and appeals research (opens in a new tab)
KFF
Independent analysis of in-network denial rates and how rarely denials are appealed on the marketplace side. Useful counterweight to vendor-published statistics.
Credentialing and enrollment
Where provider identifiers, enrollment and payer credentialing are administered.
- NPI Registry (NPPES) (opens in a new tab)
Centers for Medicare & Medicaid Services
Public lookup and management for National Provider Identifiers. A stale NPPES record is a quietly common cause of enrollment and claim rejections.
- PECOS Medicare enrollment (opens in a new tab)
Centers for Medicare & Medicaid Services
Where Medicare provider enrollment is filed and maintained. Revalidation deadlines missed here stop payment outright.
- CAQH ProView (opens in a new tab)
CAQH
The credentialing profile most commercial payers pull from. Attestation lapses here are the most frequent cause of stalled commercial credentialing.
- AAPC certification and coding resources (opens in a new tab)
AAPC
Certifying body for CPC, CPB and CPMA credentials, and a widely used reference for coding guidance and audit standards.
- AHIMA professional standards (opens in a new tab)
American Health Information Management Association
Health information management standards, including documentation integrity and clinical documentation improvement guidance.
- CLIA certification and permitted testing (opens in a new tab)
Centers for Medicare & Medicaid Services
Which laboratory tests a certificate permits a practice to bill. A test outside the certificate's scope is denied on the certificate, not on the coding.
- DMEPOS supplier standards and enrollment (opens in a new tab)
Centers for Medicare & Medicaid Services
Supplier enrollment requirements and documentation standards for durable medical equipment, prosthetics, orthotics and supplies.
Payer and program directories
Medicare contractors, Medicaid programs and coverage policy lookups.
- Find your Medicare Administrative Contractor (opens in a new tab)
Centers for Medicare & Medicaid Services
Which MAC processes your Part B claims, by state. Local Coverage Determinations vary by MAC, so this determines which medical necessity policies apply to you.
- Medicare Coverage Database (LCD/NCD) (opens in a new tab)
Centers for Medicare & Medicaid Services
Searchable national and local coverage determinations. The direct answer to whether a diagnosis supports medical necessity for a given procedure.
- State Medicaid program overviews (opens in a new tab)
Medicaid.gov
Program structure, delivery model and waivers by state. Our state pages summarise the program name and delivery model; this is the authoritative source behind them.
- Medicare Benefit Policy Manual (opens in a new tab)
Centers for Medicare & Medicaid Services
What Medicare covers and under what conditions, as distinct from how a claim is processed. The starting point for any coverage or medical necessity question.
- Medicare Secondary Payer Manual (opens in a new tab)
Centers for Medicare & Medicaid Services
When Medicare pays second, and to whom the claim goes first. Coordination-of-benefits denials are resolved here rather than with the patient.
- Medicare telehealth billing (opens in a new tab)
Centers for Medicare & Medicaid Services
Current telehealth code list, place of service and modifier conventions. This area has changed repeatedly, so the date on any secondary guidance matters.
- Workers' compensation medical billing (opens in a new tab)
US Department of Labor, OWCP
Federal workers' compensation fee schedule and billing requirements. State programs differ, but the structural rules are the same: a separate payer with its own schedule.
Privacy, security and compliance
HIPAA, enforcement, and the guidance that defines a compliant billing operation.
- HIPAA for professionals (opens in a new tab)
HHS Office for Civil Rights
The Privacy, Security and Breach Notification Rules in their authoritative form, including what a billing vendor is permitted to do with PHI.
- Sample Business Associate Agreement provisions (opens in a new tab)
HHS Office for Civil Rights
The government's own BAA language. Compare any billing company's BAA against it before signing.
- OIG compliance program guidance (opens in a new tab)
HHS Office of Inspector General
What a defensible billing compliance program looks like, including guidance written specifically for individual and small group physician practices.
- HIPAA breach portal (opens in a new tab)
HHS Office for Civil Rights
Public record of reported breaches affecting 500+ individuals. Worth searching any vendor you are about to hand PHI to.
- OIG Work Plan (opens in a new tab)
HHS Office of Inspector General
What the OIG has said it will audit and when. The clearest available signal of which coding patterns are about to receive attention.
These links are provided as references only. Vizora is not affiliated with, endorsed by, or acting on behalf of any organisation listed above, and inclusion here is not an endorsement of Vizora by them. Last reviewed August 20, 2026.
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