When billing new patient office visits, choosing the correct Evaluation and Management (E/M) code is essential for proper reimbursement. The three most commonly compared codes—99203, 99204, and 99205—represent different levels of service based on medical decision-making (MDM) or total time spent.

If you’re unsure how to differentiate them, this guide breaks them down clearly.

What Do 99203, 99204, and 99205 Represent in E/M Coding?

These codes belong to the new patient office visit category:

• 99203 – Low-level visit
• 99204 – Moderate-level visit
• 99205 – High-level visit

Since the 2021 E/M updates, providers can select a level based on either:

Medical decision-making

or

Total time on the date of service

This shift means documentation now focuses on clinical complexity, not lengthy histories or exam checklists.

What Is the Main Difference Between 99203, 99204, and 99205?

The biggest difference lies in the complexity of decision-making and the time required.

Comparison Overview

How Do the MDM Levels Differ?

Medical decision-making is determined by three factors:

1. Number/complexity of problems addressed
2. Amount and complexity of data reviewed
3. Risk of complications or morbidity

99203 – Low Complexity

A straightforward visit where the patient presents with:

• One stable chronic issue
• Or an acute, uncomplicated illness (e.g., sinus infection)

Limited data review and low risk.

99204 – Moderate Complexity

Visits involving:

• Multiple chronic illnesses
• A newly diagnosed condition requiring workup
• Prescription drug management
• Lab or imaging review

Moderate data and moderate risk.

99205 – High Complexity

Reserved for complex cases, such as:

• Serious chronic illnesses with exacerbation
• Conditions requiring intensive evaluation
• Multiple data points, specialist coordination
• High-risk decisions (e.g., hospitalization considered)

This requires significant provider expertise and high risk.

When Should a Provider Use 99203?

Use 99203 when:

• The patient has a mild or limited problem
• You order minimal tests
• There is no high-risk medication or treatment change

Example: Mild asthma flare with no complications.

When Should a Provider Use 99204?

Choose 99204 when the visit requires:

• Ordering or reviewing labs/imaging
• Managing prescription medications
• Addressing multiple medical concerns

Example: New diabetic patient requiring medication adjustment.

When Should a Provider Use 99205?

Use 99205 for the most complex new patient visits, such as:

• Suspected serious diagnoses
• Severe, uncontrolled chronic illness (e.g., uncontrolled bipolar disorder, CHF, ESRD)
• Extensive data gathering and interpretation
• High-risk treatments

Example: Patient presenting with suicidal ideation requiring safety assessment and urgent coordination with behavioral health.

Is Time-Based Coding Better for These Codes?

Not always, but it helps when:

• You spend more time counseling
• Medication management requires detailed discussion
• Care coordination or patient education takes most of the visit
• The medical decision-making is borderline

Remember: Time includes all activities performed on the date of service.

Which Code Reimburses the Highest?

Reimbursement increases with complexity:

99205 > 99204 > 99203

Payers expect clear documentation of MDM or time to support higher-level codes.

Common Documentation Mistakes to Avoid

• Listing symptoms without describing complexity
• Failing to note prescription drug decisions
• Insufficient documentation for data reviewed
• Forgetting to include all time spent on DOS
• Over-coding without clinical justification

Medicare and private payers monitor these codes closely.

Summary Comparison Chart