Written from the rule, not from a summary
Most billing explainers on the web are paraphrases of other explainers, which is how an error survives for years: nobody in the chain ever read the source, and the mistake gets more confident with each retelling. Box 24J is the standard example — half the material about it describes the wrong half of the split field.
These guides work the other way round. Each one names the rule it is describing and links where the rule is published, so you can check it rather than trust us. Where a rule genuinely has two readings — and the 8-minute rule does, because Medicare’s version and the AMA rule of eights disagree — both are given, with what each means for your units, instead of picking one and hoping your payer agrees.
They cover form fields and payer rules, which CMS publishes. They contain no CPT code list or descriptors, because that code set is licensed by the AMA and a free guide is not a licence.
When you would rather just get the number
Two of these have a calculator attached. The 8-minute rule calculator takes timed minutes per code and shows Medicare and rule-of-eights results side by side; the superbill generator turns the field explanation into something you can fill in and print. Both are free and run in your browser.
See a note turn into CMS-1500 field data
14 days, no card required. Use made-up patients while you evaluate — real patient information waits until a business associate agreement is in place.