CBCS Billing and Claims Submission 2 — Questions and Answers

Question 1: Which box on the CMS-1500 claim form is used to enter the patient's diagnosis codes?

Box 21 (Correct answer)
Box 24D
Box 33
Box 11

Correct answer: Box 21

Box 21 on the CMS-1500 contains the diagnosis codes (ICD-10-CM) for the encounter. Up to 12 diagnosis codes can be entered, labeled A through L.

Box 21 of the CMS-1500 allows entry of up to 12 ICD-10-CM diagnosis codes. Box 24E (diagnosis pointer) links each service line (Box 24D, where CPT codes go) to the applicable diagnosis code(s) from Box 21 using the letter indicators A–L. Accurate linkage ensures that each procedure is medically necessary based on the reported diagnosis. Box 21 also requires indicating whether ICD-10-CM or ICD-9-CM is being used (checked in the version indicator field).

Question 2: What is the timely filing limit for Medicare claims?

90 days from date of service
6 months from date of service
1 year (12 months) from date of service (Correct answer)
2 years from date of service

Correct answer: 1 year (12 months) from date of service

Medicare requires claims to be filed within 12 months (1 calendar year) from the date of service. Claims submitted after this deadline will be denied for timely filing.

The Medicare timely filing deadline is 12 months from the date of service (or discharge date for inpatient). For late enrollees, the period runs from the date of Medicare entitlement. Timely filing denials can sometimes be appealed if the late filing was due to administrative error (provide proof of prior timely submission). Commercial payers have their own timely filing limits (ranging from 90 days to 2 years) — always check the payer contract. Tracking filing deadlines and following up on unacknowledged claims is a key AR function.

Question 3: What is the purpose of the National Correct Coding Initiative (NCCI) edits?

To validate that diagnosis codes match the procedure codes billed
To prevent improper payment of CPT code combinations that should not be billed together on the same date of service (Correct answer)
To identify upcoded E/M services in physician billing
To check patient eligibility before claim submission

Correct answer: To prevent improper payment of CPT code combinations that should not be billed together on the same date of service

NCCI edits consist of code pair edits and medically unlikely edits (MUEs) that CMS uses to prevent inappropriate payment of bundled code combinations or unlikely units of service.

CMS developed NCCI to promote national correct coding methodologies and reduce improper payments. There are two types: Column 1/Column 2 edits (code pairs that cannot be billed together because one is a component of the other — modifier can override if clinically appropriate), and Medically Unlikely Edits (MUEs — maximum units of service per beneficiary per day for a HCPCS/CPT code). Providers can use Modifier -59 (or X{ESPU} modifiers) to override bundling edits when services are distinct. Understanding NCCI is essential for clean claims.

Question 4: What does 'crossover claim' refer to in Medicare billing?

A claim submitted to both Medicare and a commercial payer simultaneously
A claim that Medicare automatically forwards to Medicaid (or a Medigap plan) after adjudicating its portion (Correct answer)
A claim that crosses fiscal years in Medicare processing
A claim transferred from one Medicare Administrative Contractor to another

Correct answer: A claim that Medicare automatically forwards to Medicaid (or a Medigap plan) after adjudicating its portion

A crossover claim is automatically sent from Medicare to the secondary payer (typically Medicaid or a Medicare Supplement/Medigap plan) after Medicare processes the claim, eliminating the need for the provider to submit a separate claim.

Medicare has COB agreements with many supplemental payers (Medigap insurers, state Medicaid programs). When a beneficiary has Medicare and a secondary payer, Medicare forwards the claim information to the secondary payer via the Medicare COB contractor after processing. This is the 'crossover' process. Not all secondary payers participate in crossover — for non-crossover plans, the provider must submit a secondary claim manually with the Medicare RA attached. Billers should know which plans auto-crossover for their patient population.

Question 5: What information is contained in Box 33 of the CMS-1500 claim form?

The patient's diagnosis codes
The billing provider's name, address, phone number, and NPI (Correct answer)
The referring physician's name and NPI
The date and place of service

Correct answer: The billing provider's name, address, phone number, and NPI

Box 33 contains the billing provider's (or group practice's) name, address, phone number, and NPI — the entity responsible for submitting the claim and receiving payment.

Box 33 (Billing Provider Info and Ph#) includes the name and address of the practice or billing entity, phone number, and the group NPI in Box 33a. Box 33b is for the qualifier and legacy provider number if required. This is distinct from Box 31 (physician signature) and Box 32 (service facility location). When a physician works for a group, the group's NPI and address go in Box 33; the individual physician's NPI goes in Box 24J. Accurate completion of Box 33 is critical for payment routing.

Question 6: What is a secondary claim in medical billing?

A claim submitted after the primary insurer has processed and paid their portion, sent to the secondary insurer to cover remaining balances (Correct answer)
A duplicate claim submitted for the same service
A claim for a secondary diagnosis unrelated to the primary reason for the visit
A corrected claim replacing a previously submitted claim

Correct answer: A claim submitted after the primary insurer has processed and paid their portion, sent to the secondary insurer to cover remaining balances

A secondary claim is submitted to a patient's secondary insurance after the primary insurer has adjudicated the claim. It includes the primary insurance's payment information so the secondary can determine how much they owe.

For patients with multiple insurance coverage, the billing sequence is: submit to primary payer → receive RA/EOB → submit secondary claim with primary RA attached (or via crossover). The secondary claim includes the primary payment amount, adjustment amounts, and patient liability from the primary RA. CMS-1500 Box 11 indicates if there is another health benefit plan. Secondary claims must typically be submitted within a specific timeframe after the primary pays (payer-specific timely filing rules apply to secondary claims separately from primary claims).

CBCS Billing and Claims Submission 2

Which box on the CMS-1500 claim form is used to enter the patient's diagnosis codes?