Coding Guidelines

Medical coding entails the assigning and cataloging of numeric codes to relevant medical data. The diagnosis and procedural codes serve as a universal medical language along with relevant medical information about a patient for reimbursement. To properly code for a patient encounter, it is important to understand the guidelines for the Current Procedural Terminology (CPT) and the International Statistical Classification of Diseases (ICD) systems.

See guidelines for each section of coding for a patient encounter.


Find key information on ICD-10 coding guidelines and conventions, structural differences, and implementation.


Find information on the general principles of coding evaluation and management guidelines on documentation; understand the difference between the 1995 and 1997 E/M guidelines, and download E/M templates.


Learn about CPT coding guidelines for billing procedures performed in the rheumatology practice along with the correct coding for modifiers.

Coding Updates

2017 Reporting Requirements for JW Modifier

Effective January 1, 2017 providers and suppliers are required to report the Healthcare Common Procedure Coding System (HCPCS) JW modifier on Part B drug claims for discarded drugs and biologicals. Also, providers must document the discarded drugs and biologicals in the patient's medical record.

To report for reimbursement, CMS requires providers to use the JW modifier on a separate claim line. Rheumatology practices are encouraged to review their Medicare Administrative Contractor (MAC) policy as each MAC may have specific billing policies or guidance with further billing information. Keep in mind, claims for drugs furnished on or after January 1, 2017 containing billing for discarded drugs that do not use the JW modifier correctly may be subject to review or rejection.

Billing Example Using JW Modifier
A single use vial that is labeled to contain 100 units of a drug has 95 units administered to the patient and 5 units discarded. The 95 unit dose is billed on one line, while the discarded 5 units may be billed on another line with the JW modifier. Both line items would be processed for payment.

Billing Example without Use of JW Modifier
One billing unit for a drug is equal to 10mg of the drug in a single use vial. A 7mg dose is administered to a patient while 3mg of the remaining drug is discarded. The 7mg dose is billed using one billing unit that represents 10mg on a single line item. The single line item of 1 unit would be processed for payment of the total 10mg of drug administered and discarded. Billing another unit on a separate line item with the JW modifier for the discarded 3 mg of drug is not permitted because it would result in overpayment. Therefore, when the billing unit is equal to or greater than the total actual dose and the amount discarded, the use of the JW modifier is not permitted.

For additional information, review the Medicare MLN Matters MM9603 and Chapter 17 of the CMS Medicare Claims Processing Manual (Section 40) . Contact ACR coding specialists for questions or additional information on appropriate billing and coding.