Every rule on this site traces to a small number of primary sources. Each link below opens the document itself. CMS reissues several of them every year, so if a link has moved, search the title on cms.gov.
Visit levels
- AMA, 2023 E/M descriptors and guidelines. The current definitions for every E/M family: problems addressed, the data categories, the risk column and the total time rules.
- AMA, 2021 office visit code changes. The document that moved office visits to medical decision making or time.
- CMS, Evaluation and Management Services Guide (MLN006764). How Medicare applies those rules, including split or shared visits and teaching physicians.
Values and payment
- CMS, Physician Fee Schedule look-up tool. The wRVU, global period and status of any code, by year. Every value on this site is checked against it.
- CMS, CY 2026 Physician Fee Schedule final rule fact sheet. The conversion factor and the policies in force this year.
- CMS, CY 2027 proposed rule (CMS-1848-P). What is proposed for next year; nothing in it is final until the final rule.
G2211
- CMS, How to use G2211 (MLN Matters MM13473). When the add-on applies and when modifier 25 blocks it.
- CMS, G2211 frequently asked questions. The longitudinal relationship in CMS's own words.
Bundling and modifiers
- CMS, NCCI Policy Manual. Which code pairs bundle and when a modifier may separate them. Reissued every January; the edit files update quarterly.
- CMS, Proper use of modifier 59 (MLN1783722). What counts as a distinct procedural service.
Global periods and surgery
- CMS, Global Surgery booklet (MLN907166). What the 0, 10 and 90 day packages include and how modifiers 24, 25, 57, 58, 78 and 79 work.
- Medicare Claims Processing Manual, chapter 12. The operating rules for physician billing: E/M, surgery, assistants and co-surgeons.
Preventive services and counseling
- CMS, Medicare wellness visits. The Welcome to Medicare visit and the annual wellness visits, with their required elements.
- CMS, National Coverage Determination 210.4.1. Counseling to prevent tobacco use: who is covered and how many sessions.
Telehealth
- CMS, List of telehealth services. Which codes Medicare pays by telehealth this year.
- CMS, Telehealth frequently asked questions. Audio only visits, place of service and modifier 93.
Hospital quality measures
- QualityNet, complication measure methodology. The hip and knee replacement complication measure and its code lists.
- QualityNet, readmission measure methodology. The condition specific readmission measures and the planned readmission algorithm.
- AHRQ, Patient Safety Indicator technical specifications. The definitions behind each safety event.
Diagnosis documentation
- CMS, medical record reviewer guidance for risk adjustment. The standard a documented diagnosis has to meet.
- AAFP, hierarchical condition category coding. A clinician's introduction, including the MEAT rule of thumb.
How this site uses them
Each guide cites the source family it depends on at the bottom of the page, and when a source revises, the correction is made on every page and tool at once. 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.