MDM vs Time: Choosing an E/M Level Basis

No. CPT frames them as alternatives joined by "or": select the level based on the level of MDM, or on the total time on the date of the encounter. A visit with moderate MDM and 38 minutes is a 99214 either way; a visit with moderate MDM and 41 minutes is a 99215 on time alone, not because the minutes reinforced the MDM. Pick the basis that supports the level and document that basis. Trying to blend them is the fastest way to produce a note that supports neither.

MDM, for most clinicians and most encounters. It usually reflects the work more accurately, it does not require you to track a clock, and it is the only basis available in the emergency department. Time is the better answer for a specific and recognisable minority of visits: long goals-of-care discussions, extensive counselling, or days with heavy care coordination, where the thinking was not complex but the work genuinely took an hour. The practical rule is to code by MDM by default and switch to time only when you have both the minutes and a documented total.

Not for code selection. CPT requires the total time to be documented when it is used as the basis for code selection — the obligation attaches to the basis you rely on. Many practices record time habitually anyway, which is harmless and occasionally useful as a fallback. What causes trouble is a recorded time that is inconsistent with the rest of the note, because an auditor will read it even though you were not relying on it.

Because the prolonged codes measure time beyond the time required for the highest-level primary service, so they only have a coherent starting point if the primary service was itself levelled on time. CPT states this directly: 99417 and 99418 are only used when the primary service has been selected using time alone, and only after the time required for the highest-level service has been exceeded by 15 minutes. This is the one place where the choice of basis has a real financial consequence, and it is the reason a genuinely long, high-MDM visit is sometimes better levelled on time.

CPT defines an independent historian as someone such as a parent, guardian, surrogate, spouse or witness "who provides a history in addition to a history provided by the patient who is unable to provide a complete or reliable history (eg, due to developmental stage, dementia, or psychosis) or because a confirmatory history is judged to be necessary." Two details are routinely missed. First, CPT states explicitly that it "does not include translation services" — an interpreter is not an independent historian. Second, there must be a documented reason: as AAFP puts it, a patient's preference that a spouse give the history rather than the patient does not add a data point. Noridian asks you to record why the patient cannot provide a complete or reliable history, and from whom the additional history came. The history need not be obtained in person but must come directly from the historian. It counts as one Category 1 element and can be summed with tests ordered and notes reviewed.

CPT gives a closed list: preparing to see the patient, such as reviewing tests; obtaining and reviewing separately obtained history; performing a medically appropriate examination and/or evaluation; counselling and educating the patient, family or caregiver; ordering medications, tests or procedures; referring to and communicating with other health care professionals when not separately reported; documenting clinical information in the record; independently interpreting results not separately reported and communicating them; and care coordination not separately reported. It excludes the performance of other services that are reported separately, travel, and teaching that is general and not limited to discussion required for the management of this specific patient.

On time, only distinct time may be summed: CPT provides that where two or more individuals jointly meet with or discuss the patient, only the time of one individual should be counted, so a twenty-minute joint discussion contributes twenty minutes, not forty. On the Medicare side the picture changed for the better in CY2024 and many practices have not caught up. After several years of deferring a time-only rule, CMS settled on a definition aligned with CPT: for split or shared visits in facility settings the "substantive portion" means more than half of the total time spent by the physician and non-physician practitioner, or a substantive part of the medical decision making. That is now codified at 42 CFR 415.140 and was left untouched by both the CY2025 and CY2026 fee schedules. Critical care is the exception — MDM is not available there, so substantive portion means more than half the total time. Append modifier FS.

Only the teaching physician's own time counts. The Medicare Claims Processing Manual is explicit that you do not add time spent by the resident in the absence of the teaching physician, and that for visit-level selection you count only time the teaching physician spent performing qualifying activities — importantly, this does include time the teaching physician is present while the resident performs those activities. CPT separately excludes teaching that is general and not limited to the management of this specific patient. Under the primary care exception, time cannot be used at all and MDM is the only permitted basis. Where a resident is involved, MDM is often the safer basis anyway, because it scores the decision making the teaching physician actually made rather than requiring minutes to be attributed between two people.

You will see both, and the difference is real rather than a rounding of the same fact. The 2021 CPT descriptors for 99202-99215 state ranges — 99213 as "20-29 minutes," 99215 as "40-54 minutes" — and CMS still prints those ranges in its current Evaluation and Management MLN booklet and in Chapter 12 of the Claims Processing Manual. The families revised in 2023, meaning inpatient, consultations, nursing facility and home, use single minimums phrased as "must be met or exceeded," and AAFP now publishes the office codes in that same minimum form. For selecting a level nothing turns on it, because the floor is identical under both readings. It matters in exactly one place: CMS derives the G2212 prolonged-services threshold from the range maximum, which is why Medicare's prolonged thresholds sit 14 minutes above CPT's.