CPC Medical Coding cheat sheet

ICD-10-CM codes are 3–7 characters; the first character is a letter and later characters are alphanumeric, with a 7th character required for certain injury, obstetric, and external-cause codes.

In inpatient coding, the principal diagnosis is the condition established after study to be chiefly responsible for admission and is sequenced first unless a guideline directs otherwise.

In outpatient coding, the first-listed diagnosis is the condition chiefly responsible for the services provided; if no diagnosis is established, code the signs or symptoms.

Excludes1 means the two conditions cannot be reported together; Excludes2 means the excluded condition is not integral and may be reported separately when documented.

"Code also" requires an additional code to fully describe the condition; "use additional code" also instructs reporting a secondary code, with sequencing set by the guideline.

CPT Category I codes are five digits; add-on codes are marked with a plus sign, are never reported alone, and are exempt from modifier 51.

HCPCS Level II codes begin with a letter followed by four digits and cover supplies, drugs, durable medical equipment, and services not described by CPT.

ICD-10-PCS is used for inpatient procedures only; codes have seven alphanumeric characters, no decimal point, and are built from root operation and body part.

Code to the highest level of specificity supported by documentation; unspecified codes are reported only when the documentation does not support a more specific code.

New versus established patient: the patient is new if no face-to-face professional service from the same specialty and same practice occurred in the prior 3 years; otherwise the patient is established.

Office and outpatient E/M level selection may use the 1995 or 1997 documentation guidelines or, for 2021 and later, medical decision making or total time on the date of the encounter.

Modifier 25 is appended to a significant, separately identifiable E/M service performed on the same day as a procedure or other service.

Modifier 57 is used on an E/M service when the encounter results in the decision for surgery, including the preoperative evaluation.

The Medicare global surgical package includes preoperative, intraoperative, and postoperative services; 0-day, 10-day, or 90-day postoperative periods apply by procedure.

Bilateral procedures are reported with modifier 50 when the code permits bilateral designation; multiple procedures on the same day use modifier 51 on secondary procedures.

Incident-to services require direct supervision, an established patient, and an integral service under the physician's plan of care; they are reported under the physician's NPI.

Place of service codes include 11 for office, 22 for outpatient hospital, 24 for ambulatory surgical center, 21 for inpatient hospital, and 23 for emergency department.

Split or shared E/M services in facility settings require the billing practitioner to perform the substantive portion of the encounter, determined by time or medical decision making.

The False Claims Act prohibits knowingly presenting or causing false claims to government payers; penalties include treble damages and per-claim fines.

The Anti-Kickback Statute prohibits remuneration to induce referrals for federally covered items or services; the Stark Law separately bans certain physician self-referrals absent an exception.

Medicare NCCI procedure-to-procedure edits bundle column two codes into column one; a permissible modifier may bypass an edit only when documentation supports distinct services.

Modifier 59 or an X{EPSU} modifier is used for distinct procedural services, not for E/M services and not to bypass edits without supporting documentation.

Medical necessity requires documentation that supports the service as reasonable and necessary; insufficient documentation can result in denial or recoupment.

An Advance Beneficiary Notice may be issued before a Medicare service likely to be denied as not medically necessary, shifting liability to the beneficiary if the denial occurs.

HIPAA requires limiting protected health information use and disclosure to the minimum necessary and safeguarding it under the Security Rule.

Upcoding and unbundling are compliance risks because they can create false claims; internal audits compare assigned codes with supporting documentation.

Payer appeal rights and timely filing limits vary by Medicare contractor and commercial plan; denials must be appealed within the plan's stated deadline.