Primary care physicians serve as the first point of contact for patients across all age groups and conditions. This page covers the most frequently billed ICD-10-CM diagnosis codes and CPT procedure codes in primary care, family medicine, and general practice settings across the United States.
FY 2026 ICD-10-CM (CMS) · CPT codes updated annually · All codes verified billable · Last verified: June 2026
Prolonged office visit (each additional 15 min beyond minimum time)
~$33
-25
G0444
Annual depression screening, 15 minutes
~$20
-25, -59
G0439
Annual wellness visit, subsequent
~$125
-25
*Approximate 2025 CMS national non-facility rate. Rates vary by geography, setting, and payer contract. Refer to the CMS Physician Fee Schedule for official rates.
Top Denial Reasons for Primary Care Claims
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Medical Necessity Not Sufficiently Documented
Payers deny claims when the clinical record lacks documentation supporting why the visit level (e.g., 99214 vs. 99213) was medically necessary. Ensure MDM complexity or total time is fully documented in the note before billing.
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Missing or Incorrect Modifier -25
When a preventive visit (99395–99397) is billed on the same day as a problem-oriented E&M (99213–99215), modifier -25 must be appended to the problem E&M to indicate a separate, significant service. Omitting -25 results in automatic bundling denial.
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Diagnosis–Procedure Linkage Mismatch
Claims are denied when the ICD-10 diagnosis code does not support the billed procedure (e.g., billing an ECG [93000] without a cardiac or chest-pain diagnosis). Always link each procedure to a diagnosis that clinically justifies it.
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Annual Wellness Visit Billed Too Soon
Medicare Annual Wellness Visits (G0438/G0439) are only covered once per 12-month period; submitting before the beneficiary’s eligibility resets results in a frequency denial. Verify the patient’s last AWV date in the payer portal before scheduling.
Primary Care Billing & Coding Tips
Document and code all chronic conditions at every visit where they are reviewed or managed — this is required by official coding guidelines and affects quality measure performance.
Use Z00.00 for annual wellness exams without abnormal findings; use Z00.01 when abnormal findings are identified — the distinction affects documentation requirements.
Telephone and e-visit codes (99441–99443, 99421–99423) can supplement in-person visits; verify payer-specific coverage policies before billing.
Screen for social determinants of health (Z55–Z65) at preventive visits — these codes support population health programs and qualify for some value-based care incentive payments.
What is the most commonly billed ICD-10 code in primary care?
I10 (Essential hypertension), Z00.00 (Annual wellness exam), and E11.9 (Type 2 diabetes without complications) are consistently the three most frequently billed diagnosis codes in primary care settings according to CMS claims data.
Can I bill both a preventive visit and a sick visit on the same day?
Yes. Bill the preventive E&M code (99395, 99396, etc.) and the problem-focused E&M code (99213/99214) on the same day with modifier -25 appended to the problem-focused visit. Both must be separately and completely documented in the medical record.
What is the ICD-10 code for hypothyroidism?
E03.9 is Hypothyroidism, unspecified — used when the type of hypothyroidism is not documented. E06.3 is Autoimmune thyroiditis (Hashimoto’s). Code to the specific type when documented, as it affects risk stratification and medication appropriateness review.
How is nicotine dependence coded in primary care?
F17.210 is Nicotine dependence, cigarettes, uncomplicated. Z87.891 is used for personal history of tobacco dependence when the patient is no longer using tobacco. Z72.0 (Tobacco use) is used for current use that doesn’t meet the clinical threshold for dependence.
How does OmniMD support primary care?
OmniMD’s Primary Care EHR includes preventive care checklists aligned with USPSTF and HEDIS measures, chronic disease management dashboards, e-prescribing with PDMP integration, and population health analytics to help identify care gaps.
Streamline Your Primary Care Practice with OmniMD
Purpose-built EHR, billing, and practice management for Primary Care practices.
