Every load-bearing rule on this site traces to one of a small number of primary sources. This page names them, says what each one governs, and links the stable landing page where the current version lives, since the documents themselves are re-issued on annual and quarterly cycles and deep links rot.
The rulebooks that set visit levels
AMA CPT E/M Guidelines. The definitions behind everything in the MDM chapters: what counts as a problem addressed, the data categories, the risk column, and the total-time rules for every E/M family. The AMA maintains the current guidelines and revisions at its E/M coding page: ama-assn.org, Evaluation and Management (E/M) Coding. The full code descriptors live in the CPT Professional codebook, updated each January.
CMS Physician Fee Schedule. The source of every wRVU value on this site, the conversion factor, and payment policy including G2211 and the annual final rule changes: cms.gov, Physician Fee Schedule. For a specific code's current values, use the PFS Look-Up Tool linked from that page.
The rulebook that decides what bundles
Medicare NCCI Policy Manual and edit files. Every bundling verdict in the tools, modifier 59 and X-modifier policy, and the procedure-to-procedure edits, updated quarterly with the manual re-issued each January: cms.gov, National Correct Coding Initiative edits. The manual's Chapter I holds the general policies, including the modifier 25 and global period rules the site quotes.
Global periods, modifiers, and claims policy
Medicare Claims Processing Manual, Chapter 12 (Physicians and Nonphysician Practitioners). The operational rules for the global surgical package, modifiers 24, 25, 57, 58, 78, and 79, split and shared visits, and teaching physician rules. Found under CMS Internet-Only Manuals, Publication 100-04: cms.gov, Internet-Only Manuals.
Preventive services and wellness visits
Medicare Learning Network preventive services educational tools. The AWV components (G0438, G0439), advance care planning, and the preventive service requirements the wellness chapters describe. Search "MLN preventive services" from the CMS homepage for the current educational tool, which CMS revises as coverage changes.
How this site uses them
Each guide cites the source family it depends on at the bottom of the page, the public rule registry ties every tested rule to its source and effective year, and when a source revises, the change lands in What Changed with the correction stated plainly. When this site and a payer policy disagree, the payer's written policy governs that claim; these sources govern Medicare and the CPT framework itself.