How long does Trail Making Test Part B take to administer?

Typically 2–5 minutes, including a brief practice trial before the timed portion. Many protocols cap the timed trial around 150 seconds before discontinuation.

What is a "normal" score on Trail Making Test Part B?

There is no single universal cutoff. Completion time must be compared against age- and education-normed reference data from a specific normative dataset — the same raw score can be normal for one age group and abnormal for another.

What's the difference between Trail Making Test Part A and Part B?

Part A requires connecting numbers in ascending order and primarily reflects visual scanning and processing speed. Part B requires alternating between numbers and letters, adding a set-shifting and executive-function demand on top of the Part A skills. See Trail Making Test Part A for detail.

What CPT code covers Trail Making Test Part B?

It is billed as part of a battery, not as a standalone code — typically under 96136/96137 or 96138/96139 for administration and scoring, with interpretation under 96132/96133, depending on who administers it and payer policy.

Can Trail Making Test Part B be used to track recovery over time?

Yes. Because it is brief and has established normative comparisons, it is commonly used serially in concussion and TBI populations to track executive-function recovery, though practice effects and version consistency should be considered when comparing repeat administrations.

Trail Making Test Part B: Administration, Scoring & Billing Guide

Trail Making Test Part B (TMT-B) is a timed paper-and-pencil or digital neuropsychological test that measures executive function, cognitive flexibility, and divided attention by asking a patient to connect alternating numbers and letters (1-A-2-B-3-C…) in sequence as quickly as possible. Slower completion times relative to age-matched norms suggest executive dysfunction, commonly evaluated after concussion, TBI, or other neurological insult.

What Trail Making Test Part B Measures

TMT-B is the second half of the two-part Trail Making Test (see also Trail Making Test Part A, which isolates visual scanning and processing speed alone). Where Part A requires only connecting numbers in order, Part B requires the patient to alternate between two sequences — numbers and letters — switching cognitive sets on every step. This alternation demands mental flexibility, working memory to track both sequences simultaneously, and inhibitory control to suppress the urge to continue a single-sequence pattern. Because Part B layers set-shifting on top of the visual scanning and motor speed demands already present in Part A, comparing the two (commonly expressed as a B-minus-A difference or B/A ratio) is a standard way clinicians try to isolate the executive component from basic processing speed and motor output.

TMT-B sits within the Executive Function cognitive domain and is frequently paired with other executive measures such as the Stroop Color-Word Test and Verbal Fluency Test in a full neuropsychological battery.

Administration Time

TMT-B typically takes 2–5 minutes to administer. Many standardized protocols apply a discontinuation ceiling — commonly around 150 seconds — for patients who cannot complete the task in a reasonable timeframe, since prolonged struggle itself signals executive impairment. Instructions and a brief practice trial (usually 4–8 alternating items) are administered before the timed trial to confirm the patient understands the alternating pattern.

Scoring and Interpretation

The raw score is the time in seconds required to correctly complete the sequence, along with the number of errors (typically sequencing errors where the patient reverts to a single series) and the number of examiner cues needed to redirect the patient back on task. Raw completion time is converted to an age-normed T-score or percentile using published normative datasets — commonly cited sources include Heaton and colleagues' demographically corrected norms and the Mitrushina normative compendium.

There is no single universal pass/fail cutoff for TMT-B. Because normal completion time varies substantially with age, education, and the normative dataset used, a raw score is only meaningful relative to an age- and education-matched reference sample. Markedly prolonged completion time, an unusually high error count, or a large discrepancy between Part A and Part B performance relative to normative expectations are the patterns clinicians look for as indicators of executive dysfunction — not a fixed number of seconds in isolation. Norms are not interchangeable across different published normative datasets, so scores should always be interpreted against the specific reference set the clinician is using.

Clinical Use Case

TMT-B is one of the most widely used brief executive-function measures in clinical neuropsychology because it is fast, inexpensive to administer, and sensitive to diffuse brain injury — including the kind of subtle white-matter and frontal-subcortical disruption seen after concussion and mild TBI. It is a standard component of:

Post-concussion neurocognitive batteries assessing recovery of executive function over time
General dementia and mild cognitive impairment workups, often alongside the MoCA
Return-to-work and return-to-learn evaluations where sustained attention and task-switching capacity are functionally relevant (see Return to Work After Concussion and Return to Learn)
Differential workups for other conditions affecting cognition, including chemotherapy-related cognitive change and post-cardiac cognitive decline

Because TMT-B is a performance-based executive measure rather than a self-report symptom scale, it complements — rather than replaces — patient-reported instruments like the PCSS in a comprehensive concussion or cognitive-health protocol.

CPT Coding for Trail Making Test Part B

TMT-B is administered as part of a broader neuropsychological test battery rather than billed as a standalone code. Test administration and scoring are typically reported under 96136/96137 (physician or other qualified health care professional) or 96138/96139 (technician-administered), depending on who administers the test, each covering the first 30 minutes and each additional 30-minute increment of the battery. The interpretive and report-writing component — synthesizing TMT-B results with the rest of the battery into a clinical formulation — is generally reported under 96132/96133 (neuropsychological testing evaluation services). Which code family applies depends on who performs the administration, total time spent, and the specific payer's current coverage policy, so documentation should always reflect the actual administering party and time.

This page provides general educational information about CPT and RTM billing codes. It is not coding advice, a guarantee of reimbursement, or a substitute for your own compliance review. Payer coverage and documentation requirements vary by plan and can change — verify current requirements with CMS, your Medicare Administrative Contractor, and each payer before billing.

Where TMT-B Sits in the Kavera Protocol

TMT-B is one of the 14 instruments in Kavera's assessment battery, delivered as part of the Cognitive Health module and integrated into the broader Concussion module protocol where executive function tracking supports return-to-play and return-to-learn decisions. Results are captured between office visits so the trend in completion time and error pattern — not just a single snapshot — is available to the clinician at the next follow-up.

How Kavera Handles This

Trail Making B is the executive-function anchor in the Cognitive Health module, delivered on your cadence and plotted with Part A and Stroop. Kavera stores time and errors against baseline so a set-shifting trend is visible before the visit. The record supports 96136–96139 documentation. Self-Serve practices run this with their own staff. On Managed, Juliet Mott's team runs it and bills it under your credentials.

Trail Making Test Part B