Methodology
How EOBDecode works
Where the code meanings come from
Every code page has two layers, kept deliberately separate so you can see what comes from where:
- The official X12 description is transcribed verbatim from the published X12 Claim Adjustment Reason Code and Remittance Advice Remark Code lists. It is shown in quotation marks and pinned with a source link and a last-verified date.
- The plain-English layer — the meaning, typical cause, and next steps — is written by EOBDecode in plain language. It is editorial, not a quotation from X12, and it carries the reviewer workflow described below.
We treat X12 (and, for Medicare overlays, CMS) as the load-bearing primary source. Commercial billing references are used only as a cross-check and are never the sole basis for a meaning. Codes verified against X12 publications current as of June 16, 2026.
Coverage and honest limits
The X12 universe is large — hundreds of CARCs and over a thousand RARCs. EOBDecode prioritizes the codes patients see most often: 41 codes are written in plain English today (31 CARC and 10 RARC), with more added over time. When a code is not yet written, we say so rather than guessing — we do not invent meanings.
Refresh cadence
The X12 code list is revised roughly three times a year (March, July, and November). Each revision can add, retire, or amend codes. We track revisions on the changelog and re-verify the descriptions on the affected code pages, updating the last-verified date.
How appeal-letter scaffolds are built
The appeal-letter generator selects the framework for your plan type from the governing federal regulation — 29 CFR §2560.503-1 for ERISA group plans, 45 CFR §147.136 for ACA internal and external review, and 42 CFR §422.560 et seq. for Medicare Advantage — and adds a state Department of Insurance overlay for fully-insured and individual-market plans. The letter is an educational scaffold, not legal advice, and every template carries the reviewer workflow.
Editorial review
Independent editorial review is in recruitment. During this dev preview, code explanations are not yet reviewer-signed-off.
Reviewer signoff pending (dev preview)
Before this site carries advertising or is positioned for production, a credentialed reviewer — a Certified Medical Biller, patient advocate, or healthcare-billing attorney — signs off on the plain-English layer and the appeal-letter templates. See the reviewer page for the review scope and cadence.
Why this site takes its time (soak strategy)
Insurance-denial content sits in the most scrutinized category of health and financial information. EOBDecode deliberately runs a long soak before applying for advertising:
- A minimum of six months, targeting nine months, of live operation before any advertising application.
- At least two X12 revision cycles tracked and published on the changelog, to demonstrate maintenance discipline.
- A named, credentialed reviewer in place — with credential and verifiable profile — before ads or a production launch.
- An appeal-letter legal-defensibility review completed on every template.
Checkpoints are scheduled at month 1, month 3, month 6, and month 9. The operator may extend the window for additional rounds of review.
Privacy by design
The decoder and the appeal-letter generator run entirely in your browser. The codes you look up and anything you type into a letter are never sent to our servers or stored. See the privacy policy for detail.