Understanding ICD-10 and CPT Codes: Why Accuracy Matters More Than Ever

In the healthcare world, accurate billing is about more than just getting paid—it's about compliance, care continuity, and trust. Two code sets drive this process: ICD-10 and CPT codes. Together, they form the foundation of medical documentation, reimbursement, and communication between providers, payers, and regulatory bodies.

Yet, with ongoing audits, stricter payer scrutiny, and value-based care models, accuracy in coding has never been more important.

This article will help you understand what ICD-10 and CPT codes are, how they’re used, and why precision in using them is critical for every healthcare organization.

What Are ICD-10 and CPT Codes?

ICD-10: Diagnosis Codes

ICD-10 stands for the International Classification of Diseases, 10th Revision. It’s maintained by the World Health Organization (WHO) and adopted in the U.S. by the Centers for Medicare & Medicaid Services (CMS).

ICD-10 codes describe diagnoses, medical conditions, and symptoms. For example:

• F33.1 – Major depressive disorder, recurrent, moderate

• E11.9 – Type 2 diabetes mellitus without complications

• M54.5 – Low back pain

Each code communicates why a service was provided and supports medical necessity for treatments or procedures.

CPT: Procedure Codes

CPT (Current Procedural Terminology) codes are maintained by the American Medical Association (AMA). These codes describe what services or procedures were performed during a patient visit.

Examples include:

• 99213 – Office visit for an established patient (15–29 minutes)

• 90834 – Psychotherapy, 45 minutes with patient

• 36415 – Routine venipuncture

CPT codes are tied directly to reimbursement—they tell insurers how much to pay for each service rendered.

Why Accuracy Matters Now More Than Ever

Healthcare is under increasing pressure from regulatory bodies, commercial payers, and patients to deliver value-driven, transparent, and error-free services. Coding accuracy touches every one of those areas.

1. Proper Reimbursement

Incorrect or mismatched codes lead to denied claims, payment delays, and underpayments. For example:

• Using a diagnosis code that doesn’t support medical necessity for a CPT code may trigger an automatic denial.

• A missing modifier can lead to reduced or bundled payments.

When coding is accurate:

• Claims are paid faster

• Less time is spent on appeals

• Cash flow becomes more predictable

2. Audit Protection

Insurers and government payers are auditing providers more frequently, especially under risk adjustment, Medicare Advantage, and value-based payment models.

Common triggers for audits include:

• High utilization of certain CPT codes (e.g., 99215)

• Use of unspecified or vague ICD-10 codes

• Coding patterns that deviate from national averages

Inaccurate coding can result in:

• Recoupment of payments

• Fines and penalties

• Loss of in-network status

Accurate, well-documented codes reduce risk and help organizations confidently navigate compliance reviews.

3. Quality Reporting and Risk Adjustment

In today’s value-based care models, ICD-10 codes play a role in measuring patient complexity and outcomes. Risk-adjusted payment systems like HCC (Hierarchical Condition Categories) depend on precise diagnosis coding.

Accurate ICD-10 coding affects:

• Star ratings

• Capitation rates

• Shared savings calculations

• Population health management

Missing or undercoding diagnoses (e.g., not coding comorbidities like COPD or hypertension) can result in underpayment and misleading quality metrics.

4. Continuity of Care

Coding isn’t just for billing. It also:

• Informs treatment planning

• Helps coordinate care across providers

• Ensures that patient histories are accurately captured

When codes are incorrect or too vague, it can disrupt care coordination, especially in integrated health systems or shared EHR environments.

Common Coding Challenges

Despite its importance, coding remains a challenge for many practices. Some of the most frequent issues include:

1. Undercoding

Providers may use less specific codes or omit billable services out of caution. This leads to revenue loss and underreporting of patient acuity.

2. Overcoding

Using codes that don’t match documentation or inflating the level of service can trigger audits and repayment demands.

3. Unspecified Codes

While sometimes necessary, overuse of unspecified codes (e.g., F41.9 – Anxiety disorder, unspecified) can raise red flags and affect quality reporting.

4. Lack of Documentation

Even if codes are correct, if the documentation doesn’t support them, the claim is still at risk.

Best Practices for ICD-10 and CPT Coding Accuracy

Improving coding starts with systems, training, and a culture of compliance. Here are key strategies:

1. Regular Staff Training

Coding guidelines change frequently. Providers, billers, and coders should participate in ongoing education to stay current with:

• Annual CPT code updates (January)

• ICD-10 updates (October)

• CMS and payer policy changes

2. Leverage Certified Coders

Having certified coders (e.g., CPC, CCS, CRC) on your team or outsourcing to credentialed professionals ensures better accuracy, especially for complex specialties.

3. Use Technology

Modern EHRs and billing platforms often have built-in coding suggestions, alerts for incomplete claims, and AI-driven tools to catch mismatches.

However, technology is only effective when used properly—train staff on how to interpret and validate system prompts.

4. Conduct Internal Audits

Regular chart audits help catch patterns of error early. Focus on:

• High-dollar claims

• Denial trends

• High-volume procedure codes

Use the findings to create targeted training and workflow improvements.

5. Improve Clinical Documentation

Train providers to document clearly and completely, including:

• Symptoms

• Duration and severity

• Related conditions

• Specific procedures performed

Good documentation supports code selection and reduces time spent on clarifications or appeals.

Preparing for the Future

As healthcare continues to evolve toward value-based care, AI-driven coding, and real-time payment models, coding accuracy will only grow in importance. The shift means providers are not just responsible for reporting services, but for demonstrating outcomes, efficiency, and patient complexity.

Looking ahead:

• More payers will use risk adjustment for reimbursement

• Coding will influence public ratings and incentives

• Organizations that invest in strong coding foundations will perform better financially and clinically