Office ManagementCPO Exam

Billing & Coding in Optometry

Accurate billing and coding is the financial engine of an optometry practice. Every service performed must be correctly documented, coded, and billed to ensure appropriate reimbursement. Billing errors—whether undercoding, overcoding, or claim denials—directly affect practice revenue and compliance risk. The CPO exam tests your knowledge of the billing workflow, claim submission, denial management, payment posting, and billing terminology.

The Complete Billing Workflow

Eligibility Verification

Before the appointment: confirm insurance coverage, copays, deductible status, and available benefits. Reduces claim denials due to eligibility issues.

Patient Registration

Collect accurate patient demographics and insurance information at check-in. Photograph insurance cards. Verify ID.

Encounter and Documentation

Provider performs and documents the exam. Clinical documentation supports the codes assigned—documentation must justify medical necessity.

Charge Capture / Superbill

Assign CPT and ICD-10 codes. Complete the superbill. Ensure all procedures performed are captured—missed charges = lost revenue.

Claim Creation

Enter charges in the practice management system (PMS). Verify patient, provider, and payer information are correct before submitting.

Claim Scrubbing

Use a clearinghouse to "scrub" claims for formatting errors and common denial triggers before submitting to the payer. Reduces initial denial rate.

Claim Submission

Submit electronically (preferred—faster and trackable) or by paper. Confirm the payer received the claim (check clearinghouse acknowledgment).

Payment Posting / EOB Review

Receive ERA/EOB. Post payments. Flag underpayments and denials for follow-up. Verify contractual adjustments match fee schedule.

Denial Management

Identify denial reason codes. Correct errors and refile, or appeal with supporting documentation. Track denial rates and common causes.

Patient Billing

After insurance processes, bill patient for remaining balance (copay, deductible, non-covered services). Send statements on a clear schedule.

Key Billing Terminology

Allowed Amount

The maximum amount an insurer agrees to pay for a service under the provider contract.

Contractual Adjustment

The difference between the billed charge and the allowed amount; written off by in-network providers.

Copay

Fixed amount the patient pays per visit regardless of the total charge.

Deductible

Amount the patient must pay out-of-pocket before insurance begins paying (except copay services).

Coinsurance

After the deductible, the percentage split between patient and insurer (e.g., 80/20 means insurer pays 80%, patient pays 20%).

EOB / ERA

Explanation of Benefits (paper) or Electronic Remittance Advice (electronic)—payer's response to a claim.

Prior Authorization (PA)

Pre-approval required from the insurer before certain services are performed.

ABN

Advance Beneficiary Notice—required for Medicare patients before providing a service Medicare may not cover; allows balance billing.

Clearinghouse

Intermediary that processes and transmits electronic claims between providers and payers.

Timely Filing

The deadline for submitting a claim to the payer after the date of service.

Write-off

Amount removed from patient balance that cannot be collected (contractual adjustment, bad debt, etc.).

Accounts Receivable (A/R)

Total money owed to the practice; tracked by payer and age (30/60/90+ days).

Common Denials & Resolution

Denial: Patient not eligible

Resolution: Verify eligibility again; check dates; may need to bill patient directly if truly no coverage at time of service.

Denial: Duplicate claim

Resolution: Confirm the original was not paid; if separate service, add appropriate modifier (-76, -77) and resubmit.

Denial: Medical necessity not established

Resolution: Review documentation; add more specific/appropriate ICD-10 diagnosis code; appeal with supporting clinical notes.

Denial: Prior authorization required

Resolution: Obtain retroactive authorization if payer allows; appeal with clinical justification; write off if authorization cannot be obtained.

Denial: Timely filing exceeded

Resolution: Rarely appealable; review internal submission workflows to prevent recurrence; may be able to recover from secondary insurance.

Denial: Non-covered service

Resolution: Verify benefit coverage; if patient was not informed, may need to write off; if patient was informed in advance (ABN for Medicare), patient may be billed.

Practice CPO Billing Questions

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Related Resources

Coding Basics

CPT codes, ICD-10 codes, and the foundational coding knowledge needed for billing.

Vision Insurance Plans

VSP, EyeMed, Medicare, Medicaid—understanding major plan structures.

Insurance Verification

Verifying eligibility and benefits before the appointment.

CPO Exam Content Outline

Complete breakdown of CPO certification exam topics.

Frequently Asked Questions

What is the difference between a claim and a remittance advice (EOB)?

A claim is the request for payment submitted by the practice to the insurance payer—it lists the services performed (CPT codes), diagnoses (ICD-10 codes), patient information, provider NPI, and date of service. An EOB (Explanation of Benefits) or ERA (Electronic Remittance Advice) is the response from the payer—it shows which services were paid, the allowed amount, what the payer paid, what the patient owes, and the reason for any denials or reductions. Practices must reconcile every EOB against the original claim to confirm correct payment and identify underpayments, denials, or adjustments that need follow-up. EOBs sent to patients by their insurer must be read carefully—they can generate patient questions about their bills.

What are the most common reasons for claim denials in optometry and how are they resolved?

Common optometry claim denials and resolutions: (1) Patient not eligible/not covered on date of service — verify eligibility before the appointment; refile after confirming correct plan or date. (2) Duplicate claim — verify the original claim was not already paid before refiling; add a modifier if it was a separate service. (3) Missing or incorrect diagnosis code — attach the appropriate, specific ICD-10 code that supports the medical necessity of the service. (4) Non-covered service — verify what the plan covers before the visit; inform patient of self-pay cost; cannot charge more than the allowed amount for contracted services. (5) Prior authorization required — obtain authorization retroactively if allowed, or appeal with supporting documentation. (6) Timely filing limit exceeded — submit claims within the payer's deadline (varies from 90 days to 1 year); always submit promptly.

What is the timely filing limit and what happens if it is exceeded?

The timely filing limit is the deadline after the date of service by which a claim must be submitted to be considered for payment. Limits vary significantly by payer: Medicare requires claims within 12 months (1 year) of service; many commercial insurers require 90–180 days; Medicaid timely filing limits vary by state (typically 90 days to 1 year). If a claim is filed after the timely filing limit, it will be denied as "timely filing exceeded"—and this denial is typically not appealable. The practice absorbs the loss. Prevention: submit claims within 2–3 business days of the encounter, and track all outstanding claims in the accounts receivable system.

What is an Explanation of Benefits (EOB) and what information does it contain?

An EOB (Explanation of Benefits) is the document an insurance company sends to the provider (ERA/Electronic Remittance Advice) and to the patient after processing a claim. Provider EOB content includes: patient name and ID, date of service, CPT code(s) billed, billed amount, contractual adjustment (the difference between the billed and allowed amounts under the contracted fee schedule), allowed amount, amount paid by the insurer, and patient responsibility (copay, deductible, coinsurance). Denial reason codes and group/category codes are included when payment is denied or reduced. Staff must be able to read EOBs to post payments correctly, identify discrepancies, and initiate appeals or patient balance billing.

What is "balance billing" and when is it permitted?

Balance billing occurs when a provider charges a patient for the difference between their billed charges and what the insurance plan paid—beyond the patient's contracted copay, coinsurance, or deductible. For in-network providers: balance billing (above the contracted allowed amount) is generally NOT permitted under the participation contract. The practice must write off the contractual adjustment. Charging a patient the difference between the billed rate and the allowed amount would be a contract violation. For out-of-network providers: balance billing is generally permitted, though some states have balance billing protections. For non-covered services: the patient may be billed the full charge if they were informed in advance (ideally via an Advance Beneficiary Notice/ABN for Medicare patients).

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