Ot eval mod complex 45 min
CPT code 97166 covers a 45-minute occupational therapy evaluation for patients with moderate complexity conditions affecting their ability to perform daily activities. This is the mid-level evaluation code used when the patient's functional limitations require more assessment than a simple screening but less than a highly complex evaluation.
RVU breakdown
Conversion factor: 32.3465 · Source: CMS MPFS RVU25A · Confidence: High
Billing tips
Document at least 2 moderate complexity factors: 1-2 comorbidities affecting function, stable/predictable condition, evolving clinical presentation, and moderate task modification needs
Impact: Proper complexity documentation prevents $15-20 downcoding to 97165 and supports full $100.60 reimbursement
Always append modifier GO to identify this as occupational therapy service, not physical or speech therapy
Impact: Missing GO modifier results in 100% claim denial; mandatory for all OT claims including this code
Bill only once per episode of care or upon significant change in functional status; Medicare typically allows re-evaluation every 30 days or with documented clinical change
Impact: Billing frequency violations trigger audits and denials; spacing evaluations appropriately protects $100.60 per evaluation
Time-based documentation: while 97166 is not strictly timed, document face-to-face time of approximately 45 minutes to support moderate complexity level
Impact: If actual time is 20-30 minutes, auditors may downcode to 97165, costing $15-20 per claim
Track therapy cap thresholds and apply KX modifier when medically necessary services exceed annual limits ($2,230 in 2025)
Impact: Missing KX modifier after threshold causes automatic denial of entire $100.60 claim
For Medicare Advantage plans, verify pre-authorization requirements specific to evaluations before service delivery
Impact: Some MA plans require authorization even for evaluations; failure to obtain causes 100% denial ($100.60 lost revenue)
Common denials
Missing or incorrect therapy modifier (GO for occupational therapy)
How to appeal: Resubmit claim with corrected modifier GO appended; include cover letter explaining administrative error. Most payers allow corrected claims within 1 year of service date.
Frequency limitation - multiple evaluations billed within same episode without documented change in functional status
How to appeal: Submit medical records documenting significant functional change, new diagnosis, or change in treatment setting that necessitated re-evaluation. Include physician orders if available and progress notes showing measurable functional decline or improvement plateau requiring new assessment.
Insufficient documentation of moderate complexity factors - evaluation appears to meet low complexity criteria
How to appeal: Provide complete evaluation documentation highlighting: number of comorbidities, clinical stability level, environmental barriers, cognitive factors, and task modification needs. Use comparative grid showing why moderate (97166) rather than low (97165) complexity was appropriate.
Services performed by non-qualified provider (COTA performing evaluation without OTR supervision or billing independently)
How to appeal: Provide credentials of evaluating OTR, state licensure documentation, and facility policy on supervision. Re-bill under supervising OTR's NPI if originally billed incorrectly under COTA credentials. Note: COTAs legally cannot perform evaluations in most states.
Frequently asked questions
What is the difference between CPT 97165, 97166, and 97167?
These are the three occupational therapy evaluation codes based on complexity. 97165 is low complexity (20-30 minutes, 0-1 personal factors, stable condition), 97166 is moderate complexity (45 minutes, 1-2 personal factors, stable/predictable presentation), and 97167 is high complexity (60 minutes, 3+ personal factors, unstable/unpredictable condition). The 2025 Medicare rates are approximately $85, $100.60, and $115 respectively.
How much does Medicare pay for CPT 97166 in 2025?
Medicare pays $100.60 for CPT code 97166 in 2025 based on the national average non-facility rate. Both facility and non-facility rates are identical at $100.60. The total RVU is 3.11 (1.54 work RVU, 1.53 PE RVU, 0.04 MP RVU) multiplied by the 2025 conversion factor of 32.3465.
Can occupational therapy assistants bill CPT 97166?
No, Certified Occupational Therapy Assistants (COTAs) cannot perform or bill evaluations including 97166. Only licensed Occupational Therapists (OTR/L) can conduct evaluations and bill 97166. COTAs can provide treatment services under OTR supervision but evaluations and re-evaluations must be performed by the OTR.
How often can you bill 97166 for the same patient?
Medicare typically allows one initial evaluation per episode of care and re-evaluations approximately every 30 days or with documented significant change in functional status. Billing multiple evaluations within a short timeframe without justification triggers denials. Document clear medical necessity and functional changes to support additional evaluations.
What modifiers are required for CPT 97166?
Modifier GO is mandatory for all occupational therapy services including 97166 to identify the service as OT (versus GP for physical therapy or GN for speech therapy). Modifier KX is required when services exceed the Medicare therapy threshold. Other modifiers like 59 may apply in specific circumstances when billing with other procedures.
What documentation supports moderate complexity for 97166?
Documentation must show 1-2 personal factors or comorbidities affecting function, stable and predictable clinical presentation, evolving occupational performance, and moderate assistance or task modification needs. Include specific functional limitations, standardized assessment results, environmental factors, and clear justification for why the evaluation is more complex than 97165 but less complex than 97167.
Can you bill 97166 and treatment codes on the same day?
Yes, you can bill 97166 (evaluation) and treatment codes (such as 97530, 97110, 97140) on the same day of service. No modifier is typically required as evaluation and treatment are distinct services. However, ensure documentation clearly separates evaluation time/activities from treatment time/activities, and total time supports all billed codes.