Hospital price transparency
What a validator pass misses
A validator checks form: does the file parse, are the required elements present, do values match their valid lists. The CMS validator and the published schemas exist for exactly this, and running them on every republication is table stakes.
What a validator cannot check is correspondence to reality. It cannot know that a payer contract renegotiated last quarter, that the discounted cash price changed, that a rate table was missed, or that the de-identified minimum and maximum were computed from a partial plan list. Rows can carry a populated median alongside a zero count and still pass a structural check, because each field is individually well formed - the live page's zero-count finding is the standing example.
The CY 2026 attestation turns that gap into a named person's statement. The file affirms it is true, accurate and complete as of its date, and CMS can request a certification of accuracy and completeness during monitoring. A validator pass is evidence about structure. The attestation is a claim about the data.
The working rule: validate, then sample. After the file parses, pull a short list of high-volume services and trace each one from source - contract, rate sheet, cash price policy - to the encoded row. The validator keeps the file parseable; the sampling keeps it honest.