Charlene that's my confusion too. It seems 99421-99423 are covered by some insurance plans but the medicare rate for them are very little, much less than 9913. From the Updox webinar that I watched, the practices billed 99213 with POS 02 and modifier GT for interactive communication. It seems the components/documentation requirements for 99421 are much less than 99213, so maybe it depends on what was done during the visit.