Doctors often treat both sudden health problems and long-term conditions in internal medicine. To get paid correctly for the care they provide, it is important to use the right billing and coding guidelines. Acute conditions like infections or injuries need different codes than chronic conditions like diabetes or high blood pressure. This blog explains the difference between coding and billing for acute and chronic care, including which CPT codes to use, how to list diagnoses, and so on.

Chronic vs Acute Care: Coding & Billing Guidelines

Accurate billing and coding depend on a clear understanding of how services differ when managing acute conditions versus chronic conditions. The following is a detailed breakdown focused entirely on medical billing and coding practices for both care types:

• Coding Systems and Diagnosis Representation

Both acute and chronic conditions are identified using distinct ICD-10-CM codes.

Acute care conditions are typically coded using diagnosis codes that reflect the short-term and often severe nature of the condition. For example, pneumonia or a heart attack is assigned an acute diagnosis code based on its specific type, location, and severity.

Chronic care conditions are coded with long-term diagnosis codes that may also include additional codes for complications. For instance, diabetes may be accompanied by a code for diabetic nephropathy if complications are present.

When a chronic condition results in an acute exacerbation, such as in the case of chronic obstructive pulmonary disease (COPD), both the chronic condition and the acute episode should be reported together.

• Sequencing of Diagnoses

When coding for services involving both acute and chronic conditions, the sequencing of the diagnosis codes depends on the purpose of the visit.

If the patient presents primarily for treatment of an acute condition, the acute diagnosis should be listed first, even if chronic conditions are also documented. On the other hand, if the visit is for routine management of a chronic illness, such as diabetes follow-up, the chronic condition becomes the primary diagnosis.

In cases where a patient with a chronic illness presents with an acute complication or exacerbation (such as diabetic ketoacidosis), the acute issue should be coded first, followed by the underlying chronic disease.

• CPT Code Selection

CPT codes are used to report the services rendered during a patient encounter and differ significantly between acute and chronic care.

Acute care services: The following CPT codes are commonly used:

• 99221–99223: These codes represent initial inpatient or observation care, with varying levels of complexity and time (ranging from ~30 to ~70 minutes).


• 99231–99233: These codes are used for subsequent hospital or observation follow-up visits and are based on the complexity of the assessment (ranging from ~25 to ~50 minutes).


• 99238–99239: These codes apply to hospital discharge day management, covering all discharge-related tasks, with 99238 used for 30 minutes or less, and 99239 for services exceeding 30 minutes.


• 99281–99285: These codes are used for emergency department services and are based on the severity and complexity of the presenting problem, from minor issues to life-threatening conditions.

Chronic care management (CCM) services: The appropriate CPT codes include:

• 99490: Used for 20 minutes of clinical staff time per calendar month for patients with two or more chronic conditions.


• 99439: An add-on code for each additional 20 minutes of clinical staff time. It must be billed with 99490 and can be used up to two times per month.


• 99491: Represents 30 minutes of CCM provided directly by a physician or qualified healthcare professional. This code must meet CCM eligibility and includes the development and management of a comprehensive care plan.


• 99437: An add-on code used with 99491 for each additional 30 minutes of provider-delivered CCM. It can be billed up to two times per month and must meet the same documentation standards as 99491.


• G0511: This code is used by Rural Health Clinics (RHCs) and Federally Qualified Health Centers (FQHCs) to bill for general care management services. It reflects services similar to 99490 and 99439 but is being retired as of July 1, 2025. After this date, RHCs and FQHCs must use standard CCM codes (99490, 99439, 99491, or 99437).

Complex CCM: This involves more detailed planning and clinical oversight with the following applicable codes:

• 99487: Represents 60 minutes of complex CCM services provided under general supervision.


• 99489: An add-on code for each additional 30 minutes of complex CCM. It must be billed with 99487 and cannot be used independently.

Important note: Complex CCM codes (99487, 99489) cannot be billed together with non-complex CCM codes (99491, 99437) for the same patient in the same calendar month. Providers must choose one category based on complexity and the level of involvement.

• Billing Frequency and Service Time

Acute care services: CPT codes are typically billed per encounter or per day, depending on the setting and nature of the service. Time-based billing is allowed for inpatient codes if more than 50% of the encounter is spent in counseling or coordination of care.

Chronic care services: Billing is generally done monthly, and the total time spent on non-face-to-face services must be documented. Clinical staff or provider time must be tracked accurately to support the code billed.

• Documentation Requirements

Acute care billing: Documentation must include a chief complaint, comprehensive history, physical examination, and medical decision-making complexity. In emergency and inpatient care, all relevant findings and actions must be documented clearly to justify the level of service billed.

Chronic care management billing: Providers must document the patient’s qualifying chronic conditions, the care plan developed, time spent on services, and ongoing coordination with other health professionals. Codes like 99491 and 99437 require that the provider personally delivers the service and manages the care plan directly.

• Use of Z Codes

Z codes are used in chronic care billing to represent encounters for long-term therapy or medication use. For example,

• Z79.4 is used for long-term insulin therapy,


• Z51.81 can be used for encounters related to chemotherapy or radiation therapy.

These codes should be used in addition to the primary chronic condition codes to fully capture the reason for the visit or ongoing care.

Acute care settings: Z codes are not commonly used unless follow-up or preventive counseling services are involved.

• Use of Modifiers

Modifier codes are often required when acute and chronic care services are delivered during the same visit.

• Modifier 25 is used to indicate a significant, separately identifiable E/M service provided on the same day as another procedure or service.


• Modifier 59 is used to indicate distinct procedural services that would otherwise be bundled together.

Proper use of modifiers ensures that both acute and chronic services are reimbursed when appropriate and not denied due to bundling rules.

• Reimbursement Differences

Chronic care codes offer monthly reimbursements based on time and provider involvement. The average 2025 reimbursement for:

• 99490 is approximately $60.49


• 99439 pays $45.93 per unit (up to two units)


• 99491 reimburses more than 99490, as it reflects physician-level involvement


• G0511 (until July 1, 2025) averages $74.20 nationally

Although G0511 is being retired, clinics can use a combination of 99490 and 99439 to match previous reimbursement levels.

Acute care visits often result in higher per-encounter reimbursement, especially when services are provided in the hospital or emergency department. For example, CPT 99223 for high-complexity inpatient admission may reimburse more due to the time and complexity involved.

Conclusion

It is important to ensure accurate and correct medical billing and coding for acute and chronic conditions. It starts with clear and complete documentation from healthcare providers. Using the correct codes and following the latest rules helps avoid mistakes and claim denials. When a chronic condition gets worse, it is also important to code both the chronic condition and the new problem correctly. Moreover, regular checks and trained coders can help catch and fix issues early. 24/7 Medical Billing Services make this process even easier for you. Our team stays up to date with all the latest coding changes and knows how to handle both simple and complex cases.

Do you need help improving your acute or chronic care billing?

Outsource medical billing and coding services to 24/7 Medical Billing Services.

FAQs

Q1. Do chronic care codes apply to mental health conditions?

Chronic mental health conditions can be billed using CCM codes if they meet eligibility.

Q2. Can acute condition billing be done via telehealth?

Only certain low-severity acute visits may be eligible for telehealth billing.

Q3. What is the most common error when billing both acute and chronic conditions?

Failing to sequence the diagnoses properly is a common mistake.

Q4. Are time logs required for chronic care billing?

Accurate time tracking is essential for proper billing of CCM codes

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