CMS has never given an exact time frame, but says they should be signed after a reasonable transcription process. 30 days after the note is transcribed in the EMR is nowhere near reasonable. Every doctor I have ever billed for does their transcription and signs off on the record same day or next day. Anything beyond 2-3 days is moving out of a "reasonable" area, and would not go over well with CMS, I don't imagine.