Prescription Rejections and Coordination of Benefits: Finding the Primary Plan

What the Rejection Is Actually Saying

When a pharmacy receives a coordination-of-benefits rejection at the point of sale, the adjudication engine has not evaluated the drug’s clinical efficacy, checked prior authorization criteria, or decided that the patient lacks coverage. Instead, the payer is declaring an order-of-liability refusal to adjudicate: the claim was presented out of sequence, and the processor refuses to process payment until the legally or contractually primary insurer has evaluated the prescription.

In commercial pharmacy operations and market access, confusing a COB rejection with a benefit denial is a costly operational error. Submitting a clinical appeal, requesting an emergency formulary exception, or soliciting prescriber letters of medical necessity will not resolve a COB block. The claim engine halts at the eligibility routing layer before reaching medical policy logic. Until the primary payer is billed or the underlying coverage database is updated, the claim will reject repeatedly.

To resolve these rejections efficiently, access specialists and specialty pharmacy billing teams must distinguish between the two core roles in multi-plan coordination:

• Primary Payer: The health plan, statutory program, or insurer legally obligated to process and pay covered healthcare claims first, up to its contractual benefit design, without regard to whether the beneficiary holds other insurance.

• Secondary Payer: An insurer or assistance program that adjudicates covered liabilities remaining after the primary payer has processed the claim, paying balances such as copayments, coinsurance, and deductibles according to its own coordination terms and formulary rules.

Every multi-payer transaction involves three distinct operational layers that must stay in alignment: the real-time point-of-sale transaction, the remittance explanation, and the underlying master enrollment records. When these layers conflict, rejections occur immediately.

Read the Code Before You Call Anyone

Before calling a plan help desk or telling a patient that coverage has lapsed, read the reject code the switch returned. NCPDP reject codes describe the claim defect. State Medicaid programs then map those codes onto their own edit numbers.

Point-of-Sale Rejections vs. Remittance Denials

A fundamental technical distinction exists between real-time pharmacy transactions and medical claims processing. In retail and specialty pharmacy, claims adjudicate through the NCPDP Telecommunication Standard Version D.0, where the switch returns the rejection in the same point-of-sale transaction. In contrast, institutional medical billing and buy-and-bill drug administration rely on the X12 837 claim transaction, where adjudication outcomes appear asynchronously on the X12 835 electronic remittance advice.

While medical billers frequently encounter X12 Claim Adjustment Reason Code 22 (CARC 22) (“This care may be covered by another payer per coordination of benefits”), pharmacy operators receive specific numeric NCPDP reject codes that define whether the issue is an unbilled primary insurer, a malformed secondary claim segment, or an internal data discrepancy.

NCPDP Reject Code Families for Coordination of Benefits

The following table maps the standard NCPDP reject codes, field error codes, and remittance codes encountered during prescription coordination, along with their underlying technical cause and required operational resolution.

State Medicaid Edit Variations: NYRx, Medi-Cal, and State Crosswalks

While the national NCPDP standard establishes baseline reject codes, state Medicaid fee-for-service programs implement unique edit tables within their Medicaid Management Information Systems (MMIS). Billing teams operating across multiple states must account for these proprietary mappings:

• New York State (NYRx): Under NYRx pharmacy guidance, when a Medicaid beneficiary has commercial coverage or Medicare, the system triggers NYRx Edit 01631 (“Client Has Other Insurance”). This internal MMIS edit maps to NCPDP Reject 13 and returns MEVS Denial Code 717. NYRx enforces strict third-party liability cost avoidance: the pharmacy must bill all other payers first. Crucially, NYRx policy provides that if a commercial primary payer makes a payment toward the prescription, NYRx can adjudicate secondary cost-sharing without requiring a separate NYRx prior authorization.

• California (Medi-Cal Rx): The California Department of Health Care Services (DHCS) maintains an Other Health Coverage (OHC) database. Medi-Cal Rx automatically blocks claims if an active OHC code exists on the beneficiary’s master eligibility file. The documented Medi-Cal Rx billing order requires: 1) Other Health Coverage first, 2) Medicare second, and 3) Medi-Cal Rx last. The secondary submission must carry the primary carrier ID and the complete electronic response.

• Connecticut DSS and Pennsylvania DHS: State interchange documentation explicitly crosswalks MMIS edit rules to NCPDP 41 and 8W. In Connecticut, an MMIS edit indicating third-party liability generates NCPDP Reject 41 with custom narrative text specifying whether private insurance or Medicare Part D must be billed.

Who Pays First: The Master Decision Matrix

Federal MSP rules, 42 CFR 433.139, the NAIC Coordination of Benefits Model Regulation, and TRICARE’s published order each decide a defined coverage combination. The table names the governing source on every row. The NAIC model binds a commercial pair only where the state or the plan has adopted it.

The Cross-Program Payer Order Table

Visual Adjudication Hierarchy

flowchart TD
  Start["Prescription rejects for coordination of benefits"] --> Records["List every active coverage record"]
  Records --> Esrd{"ESRD coordination period still open?"}
  Esrd -->|Yes| EsrdPay["Group, retiree, or COBRA plan pays first for up to 30 months"]
  Esrd -->|No| Aged{"Age-65 Medicare with current-employment group coverage?"}
  Aged -->|"Employer has 20 or more employees"| Ghp["Group plan pays first"]
  Aged -->|"Fewer than 20 employees"| MedFirst["Medicare pays first, unless a multi-employer plan meets the 20-employee test"]
  Aged -->|No| Disab{"Disability Medicare with current-employment coverage?"}
  Disab -->|"Large-group 100-employee test met"| Lghp["Large group plan pays first"]
  Disab -->|"Below the 100-employee test"| MedDis["Medicare pays first"]
  Disab -->|No| Other{"Another combination on the decision table?"}
  Other -->|"Retiree coverage, or COBRA with age or disability Medicare"| Retiree["Medicare pays first"]
  Other -->|"Two commercial plans"| Comm["Non-dependent plan pays first, then apply the birthday rule for a child"]
  Other -->|"Medicaid plus other coverage"| Caid["Bill the other payer first, then Medicaid"]
  Other -->|"TRICARE with pharmacy other insurance"| Tri["Other pharmacy insurance pays first"]
  EsrdPay --> Resubmit["Keep the primary response and resubmit the secondary claim with the other-payer fields"]
  Ghp --> Resubmit
  MedFirst --> Resubmit
  Lghp --> Resubmit
  MedDis --> Resubmit
  Retiree --> Resubmit
  Comm --> Resubmit
  Caid --> Resubmit
  Tri --> Resubmit

The Documents That Govern Each Row

Every row in the master decision matrix is anchored by binding legal authority and specific plan documentation. Pharmacy operations teams must know where to locate these evidentiary sources when disputing a payer rejection or proving liability.

Medicare Secondary Payer Statutory Thresholds

The Medicare Secondary Payer (MSP) provisions of the Social Security Act (42 U.S.C. § 1395y(b)) establish exact employee thresholds that dictate whether an employer group health plan pays before Medicare. These numbers are strict statutory lines, not discretionary plan guidelines:

• The 20-employee line (working aged): 42 CFR 411.172 makes Medicare secondary when the person is aged and entitled to Part A, coverage under the group health plan is by virtue of the person’s or spouse’s current employment, and the employer has at least 20 employees. A multi-employer plan is included when at least one participating employer has at least 20 employees. Medicare pays first for a smaller employer outside that test. Under 411.172(b), a multi-employer plan may request an exception, and identify the people covered through a participating employer with fewer than 20 employees. A person who refuses the employer plan has Medicare as the primary payer.

• The 100-employee line (disability): 42 CFR 411.101 defines a large group health plan as coverage for employees of an employer that employed at least 100 full-time or part-time employees on 50 percent or more of its regular business days during the previous calendar year, or a multi-employer arrangement in which at least one employer met that test. 42 CFR 411.204 makes Medicare secondary to that plan when the person is entitled to Medicare because of disability and has the coverage by virtue of current employment of the person or a family member. CMS product 02179 says Medicare pays first below that threshold. 42 CFR 411.200 is the statutory-basis section for the disability subpart. When the person is also eligible for Medicare because of ESRD, the ESRD rules apply.

• The ESRD coordination period: 42 CFR 411.162 makes Medicare secondary to any group health plan, including a retirement plan, for a person entitled to Medicare on the basis of ESRD during the coordination period. Employer size and employment status do not change that order. CMS product 02179 describes a period of up to 30 months after the person is first eligible for Medicare because of ESRD. During the period, the group plan, retiree plan, or COBRA pays first, including when the plan’s own terms say it pays second to Medicare. After the period, Medicare pays first. The regulation also states that Medicare benefits are not payable for a person who is eligible and not yet entitled.

Commercial Coordination: NAIC Birthday Rule and Custodial Decrees

For patients covered by two commercial employer plans, coordination is governed by state insurance regulations modeled on the NAIC Coordination of Benefits Model Regulation (#120). When dependent children are covered under both parents’ health plans, two primary rules apply:

• The Birthday Rule: For dependent children whose parents are married or living together, the plan of the parent whose birthday falls earlier in the calendar year is primary. The birth year is entirely excluded; only month and day are compared (e.g., a parent born July 12, 1985 pays before a parent born September 3, 1982). If both parents have the same birthday, the plan that has covered a parent longer pays primary.

• Separation, divorce, and parents who are not living together: under NAIC Model Regulation #120, a court decree that assigns health-care responsibility to one parent controls once the plan has actual knowledge of it. If that parent has no coverage for the child and that parent’s spouse does, the spouse’s plan is primary. When the decree makes both parents responsible, or states joint custody without assigning health-care responsibility, the birthday rule decides. With no decree allocating responsibility, the order is the custodial parent’s plan, then the custodial parent’s spouse, then the non-custodial parent, then the non-custodial parent’s spouse. The model applies only as adopted by the state and written into the plan.

Medicaid Cost Avoidance Under 42 CFR 433.139

Federal law under 42 CFR 433.139 mandates that state Medicaid agencies practice strict cost avoidance When the agency has established the probable existence of third-party liability at filing, 42 CFR 433.139(b)(1) requires it to reject the claim and return the claim to the provider for a determination of liability. The agency then pays to the extent its payment schedule exceeds the third party’s payment. Paragraph (b)(3) uses pay-and-pursue recovery for preventive pediatric services, including EPSDT, where a state may wait 90 days when that wait is cost-effective and consistent with access, and for specified title IV-D child-support services, where the provider certification can run up to 100 days and the state may pay within 30 days when that is cost-effective and needed for access. Paragraph (e) allows a cost-effectiveness waiver of specified cost-avoidance requirements.

Where Records Live and How to Retrieve Them

To verify which plan is on record before submitting claims, billing specialists utilize three primary technical repositories:

• Electronic 270/271 Transactions: The real-time HIPAA 270 Eligibility Inquiry returns an electronic 271 response containing Loop 2110C and EB segments. These segments indicate active Other Health Insurance, policy numbers, and primary payer BIN/PCN qualifiers.

• CMS Common Working File (CWF): For Medicare beneficiaries, the master MSP auxiliary record is maintained on the Common Working File. This file is populated via mandatory Section 111 reporting by insurers and employer plans, as well as questionnaires processed by the BCRC.

• State Medicaid TPL Portals: State provider portals (such as the Medi-Cal Rx Provider Portal or New York eMedNY) allow credentialed pharmacies to look up Third Party Liability carrier codes and verify active commercial health plans recorded on the state’s master client database.

Worked Record: From Reject 13 to a Resubmitted Secondary Claim

To illustrate the precise transaction mechanics, consider a realistic pharmacy billing scenario using labeled placeholder data.

Step 1: Intake and Initial Rejection

The pharmacy transmits an initial D.0 billing transaction to Medicare Part D (Plan B). Within seconds, the switch returns an electronic rejection:

• Transaction Status: Rejected (R)

• Reject Code 1: 41 (Submit Bill To Other Processor Or Primary Payer)

• Reject Code 2: 13 (M/I Other Coverage Code)

• Payer Message: “Active Commercial GHP on file. Medicare is Secondary Payer. Bill Primary First.”

Step 2: Primary Claim Submission and Adjudication Capture

Applying 42 CFR 411.172, the example employer has 50 employees, so the commercial group plan is primary for this working-aged beneficiary. Every routing and dollar field below is a labeled placeholder: BIN 999999, PCN EXAMPLE, Group PLACEHOLDER, and Cardholder ID EXAMPLE0001. None of those values is a live payer identifier. The example gross charge is $1,800.00.

The primary commercial payer adjudicates the claim and returns a Paid response:

• Primary Gross Amount Billed: $1,800.00

• Primary Allowed Amount: $1,200.00

• Primary Amount Paid (Field 431-DV): $1,150.00

• Primary Patient Responsibility (Copay / Coinsurance): $50.00

Step 3: Formatting the NCPDP D.0 Secondary Claim Segment

The pharmacy now resubmits the secondary claim to Medicare Part D. To satisfy coordination rules and avoid Reject 13 or 8W, the claim must include the NCPDP Version D.0 Coordination of Benefits / Other Payments Segment with the exact fields shown in the table below.

Step 4: Secondary Adjudication Outcome

Once the secondary claim carries a coordination segment that matches the primary response, the Part D plan adjudicates the remaining patient responsibility under its own benefit, formulary, and utilization rules. In this example the primary response left a $50.00 copay. Part D may pay all, part, or none of that amount. The example stops at the fields required for resubmission and does not assign a Part D paid amount.

Fixing the Coverage Record: Program-by-Program Action Guide

A stale enrollment record produces the same reject as a claim sent to the wrong plan. Retirement, a job change, or aging into Medicare can leave a former employer plan on the payer’s file. Rebilling the same payer against that record returns the same reject. Update the record with the office that holds it, then resubmit.

Attempting to rebill the same payer repeatedly without fixing the root enrollment record will result in an identical rejection every time. Billing teams must initiate formal record updates with the appropriate program authorities.

Medicare: The Benefits Coordination & Recovery Center (BCRC)

For people with Medicare, the Benefits Coordination & Recovery Center collects other-insurance information and establishes Medicare Secondary Payer occurrence records on the Common Working File. The CMS coordination overview, last modified February 12, 2026, states that the BCRC does not process claims. Medicare Administrative Contractors process fee-for-service claims. The Commercial Repayment Center recovers mistaken group-health-plan payments.

• Contact Channel: Phone: 1-855-798-2627 (TTY: 1-855-797-2627), operating Monday through Friday, 8:00 AM to 8:00 PM Eastern Time.

• CMS product 11546 tells the beneficiary what to report to the BCRC: the person’s name, the health or drug plan’s name and address, the policy number, and the date coverage was added, changed, or stopped, and why. Tell the pharmacy and other providers about the same change before the next fill.

• The BCRC customer-service line published by CMS is 1-855-798-2627, TTY 1-855-797-2627, Monday through Friday, 8:00 a.m. to 8:00 p.m. Eastern Time, except holidays. CMS product 11546 does not set a number of days before a pharmacy claim will accept the new order. Resubmit after the coverage record used for the claim shows the corrected payer. A follow-up call is sometimes needed before that record matches the report.

Commercial Plans and PBMs: Clearing Stale Active-Coverage Flags

When two commercial plans disagree about which pays first, use the plan’s coordination terms and the state’s adoption of the NAIC order. Contact the plan that returned the rejection and ask which term it applied. An unanswered coordination questionnaire is that plan’s administrative process. It does not give reject 41 one national cause.

The document that clears a commercial coverage record is the document that plan requests. An employer or insurer letter showing the coverage end date is a common record. The plan sets the posting time. The sources for this article do not establish a 24-hour or 72-hour national clearing standard.

State Medicaid Programs: Other Health Coverage (OHC) Removal

When Medi-Cal still lists commercial pharmacy coverage after that coverage has ended, the claim keeps failing until the Other Health Coverage record changes. The April 8, 2022 Medi-Cal Rx bulletin tells the prescriber, pharmacy, or beneficiary to use the DHCS Other Health Coverage page and select the OHC Removal Form when the beneficiary has no other pharmacy coverage. The bulletin is a California example from that date. Current billing instructions are in the Medi-Cal Rx Provider Manual.

The same bulletin points to the OHC online step-by-step reference guide and to the instructions for adding or removing other health coverage. It tells the pharmacy to include the primary payer ID and the other payer’s response after a partial payment or a denial. It does not publish a processing-time standard in the bulletin text reviewed here.

TRICARE: Submitting the Other Health Insurance (OHI) Form

When other health insurance includes pharmacy benefits, the TRICARE newsroom article of August 15, 2023 says that insurance pays first and TRICARE pays second. Submit the TRICARE claim after the other insurance has processed it. The same article says to file with TRICARE first for Medicaid, TRICARE supplemental plans, state victims-of-crime compensation programs, and other federal government programs identified by the Defense Health Agency. Active-duty service members do not coordinate TRICARE as secondary coverage to other health insurance. For pharmacy benefits, complete a TRICARE Other Health Insurance form and mail it to Express Scripts, the pharmacy contractor named in that article. The regional contractor also accepts an other-health-insurance questionnaire by phone, online, or by mail or fax.

Medicare Part D Specifics: TrOOP, Confidentiality, and Reverse-and-Rebill

Coordination of benefits under Medicare Part D involves unique statutory and financial accounting rules governed by the CMS Medicare Prescription Drug Benefit Manual, Chapter 14 (Revision 17). Access teams must navigate three specialized Part D coordination requirements.

True Out-of-Pocket (TrOOP) Accounting Rules

Part D plans track True Out-of-Pocket cost to place the beneficiary in the correct benefit phase. The public Chapter 14 PDF dated September 17, 2018, section 30.2, crosswalks other payers to TrOOP eligibility. The two bullets below report that 2018 crosswalk. A later statutory change, described after the list, governs 2026 accumulator questions.

• 2018 payments marked TrOOP-eligible: In Table 30.2-2 of the September 17, 2018 Chapter 14 compilation, the supplemental payers marked TrOOP-eligible are Indian Health Service and tribal coverage effective January 1, 2011, charities, qualified state pharmaceutical assistance programs, and AIDS Drug Assistance Programs. Beneficiary cost sharing is an incurred cost. This is the 2018 crosswalk.

• 2018 exclusions and the 2026 incurred-cost rule: The same 2018 tables mark supplemental commercial insurance, Medigap, non-working health reimbursement accounts, Federal Employee Health Benefits supplemental coverage, and non-qualified state pharmaceutical assistance programs as not TrOOP-eligible. Workers’ compensation is listed as primary for the drugs it covers. Section 11201 of the Inflation Reduction Act amended the incurred-cost definition. CMS’s April 1, 2024 HPMS memorandum on TrOOP changes states that other health insurance and enhanced alternative supplemental coverage count toward TrOOP, and that low-income subsidy support, qualified state pharmaceutical assistance programs, the Indian Health Service and certain other Native American organizations, and AIDS Drug Assistance Programs continue to count. Use that memorandum for a 2026 accumulator question.

Section 30.3 of the same 2018 chapter tells Part D sponsors to follow Medicare Secondary Payer law and other payer-of-last-resort laws, and otherwise the NAIC coordination model, when they set order of payment. Order of payment and TrOOP eligibility are separate columns in that chapter. For benefit-year 2026, the incurred-cost definition in the April 1, 2024 CMS memorandum controls which of those payments accumulate.

Pricing Confidentiality in Multi-Payer Coordination

Chapter 14 section 50.14.4 states the pharmacy-pricing confidentiality rule for initial claims: coordination of benefits reports to the Part D sponsor only the beneficiary’s payment after the supplemental payment. The sponsor estimates the supplemental payment as the difference between Part D cost sharing and that beneficiary payment. That rule describes the initial coordination report. A pharmacy billing Part D as the secondary payer still sends the primary plan’s paid amount in the coordination segment, as the worked example shows.

Retroactive Adjustments and Reverse-and-Rebill Mechanics

When payer order is corrected after claims have already paid, Chapter 14 section 50.14.3 treats the result as a retroactive adjustment. Adjustments inside the payers’ timely filing windows may be handled by a pharmacy reverse and rebill. The manual says the Part D timely filing window must be at least 90 days, and another payer’s window may be as short as 30 days. Sponsors generally limit pharmacy reprocessing to payment errors. Reverse and rebill covers a portion of retroactive adjustments.

Where the pharmacy does not reprocess the claim, section 50.14.4 says the sponsor works the adjustment with the other payer. The manual states that electronic standards were not available for timely, reliable, and precise coordination on adjusted claims involving multiple payers, and that sponsors remain responsible for best-effort coordination. Section 50.14.5 says that when the pharmacy’s total payment was correct and only the split between sponsor and beneficiary changes, the sponsor re-adjudicates the claim in its own system.

When This Is a Different Problem: Clinical and Benefit Boundaries

Access specialists frequently encounter complex rejections that resemble coordination-of-benefits issues but represent entirely different operational, formulary, or benefit boundaries. Before embarking on a multi-payer investigation, verify that the claim does not fall into one of the following distinct categories:

• Formulary Exclusions and Prior Authorization: A benefit reject is a coverage-policy result. NYRx documents NCPDP reject 75 as Prior Authorization Required. Read the payer-sheet description for any other coverage reject, including reject 70, before treating it as a formulary status. For the electronic data elements used in specialty-drug prior authorization, see FHIR prior authorization data fields that cause specialty drug denials.

• Medical vs. Pharmacy Benefit Routing: When an injectable or infused biologic rejects at the retail pharmacy counter because the payer mandates administration in an outpatient clinic under buy-and-bill (J-code), the claim belongs to the medical benefit rather than the pharmacy benefit. Review our decision guide on benefit verification for specialty drugs: medical vs pharmacy benefit.

• Medicare Hospice Carve-Outs: When a patient is enrolled in Medicare hospice, drugs related to the terminal prognosis must be covered under the hospice per diem (Part A) rather than Part D, triggering specialized condition codes. See our detailed breakdown in Hospice and Part D Drugs: How Relatedness Affects Billing.

• Medicare Prescription Payment Plan (MPPP) Smoothing Failures: While MPPP opt-in programs utilize secondary claim mechanics to distribute high out-of-pocket costs into monthly installments, an MPPP failure is an enrollment program error rather than an order-of-liability dispute. See Medicare Prescription Payment Plan opt-in failures at the pharmacy.

• Manufacturer Copay Accumulators and Maximizers: When secondary copay assistance cards are rejected or do not count toward annual deductibles due to PBM benefit design rules, consult our operational guide on specialty-drug copay accumulator appeal workflows.

• New-to-Market Payer Blocks: When newly approved specialty therapies encounter immediate 180-day review blocks pending P&T review, see our strategy guide on new-to-market payer blocks in the first 180 days.

• GLP-1 Class Coverage Verification: For complex anti-obesity and diabetes benefit verifications involving strict BMI documentation, step edits, and PA rules, refer to our GLP-1 benefit investigation workflow.

Sources

The analysis, statutory thresholds, transaction code maps, and coordination workflows in this guide are derived from the following primary regulatory, standard, and payer source documents:

• Centers for Medicare & Medicaid Services. Coordination of Benefits (Medicare Secondary Payer overview). Comprehensive overview of statutory MSP provisions, Section 111 mandatory insurer reporting, and COBA national crossover program operations (last modified February 2026).

• Medicare.gov (CMS). How Medicare works with other insurance. Master beneficiary guidance defining primary and secondary payer responsibilities, BCRC contact protocols (1-855-798-2627), and conditional payment standards.

• Centers for Medicare & Medicaid Services. How Medicare Works with Other Insurance (CMS Product 02179). Official CMS guide detailing statutory employer size thresholds (20-employee line for working aged, 100-employee line for disability), 30-month ESRD coordination rules, and retiree coverage hierarchy.

• Medicare.gov (CMS). Medicare’s Coordination of Benefits: Getting Started (CMS Product 11546). Official guidance detailing required reporting data elements for BCRC coverage updates and military TRICARE coordination.

• Office of the Federal Register / CMS. 42 CFR 433.139 - Payment of claims (Medicaid third party liability). Electronic Code of Federal Regulations establishing mandatory Medicaid cost avoidance, third-party liability rejection rules, and narrow pay-and-pursue exceptions.

• California Department of Health Care Services. Medi-Cal Rx Coordination of Benefits (COB) Reminder. Bulletin dated April 8, 2022. Billing order for a beneficiary with other health coverage and Medicare is other health coverage, then Medicare, then Medi-Cal Rx. Medi-Cal Rx is payer of last resort unless the beneficiary also has California ADAP. The OHC removal path in the bulletin is the DHCS Other Health Coverage removal form.

• New York State Medicaid / NYRx. NYRx Pharmacy Rejections - How to Identify and Resolve. Technical crosswalk mapping NYRx Edit 01631 and MEVS Denial 717 to NCPDP Reject 13, and defining secondary payment without prior authorization after primary commercial payment.

• Connecticut Department of Social Services. Pharmacy NCPDP Reject Codes. Connecticut crosswalk, reviewed September 25, 2026, for NCPDP reject 41 (submit bill to other processor or primary payer), reject 8W (discrepancy between the Other Coverage Code and Other Payer Amount Paid), and reject A6 (the product or service may be covered under Medicare Part B). NYRx documents reject 13.

• Pennsylvania Department of Human Services. NCPDP Reject Error Codes. State technical specification defining coordination-of-benefits segment field error codes (4C, 5C, 5E, 6C, 6E).

• Centers for Medicare & Medicaid Services. Medicare Prescription Drug Benefit Manual, Chapter 14 - Coordination of Benefits (Rev. 17). Public PDF compiled September 17, 2018. Section 30.2 is the TrOOP crosswalk, section 30.3 is the order-of-payment standard, and section 50.14 is the confidentiality and retroactive-adjustment discussion. The 2018 TrOOP rows predate the incurred-cost amendment described in CMS’s April 1, 2024 HPMS memorandum.

• National Association of Insurance Commissioners. Coordination of Benefits Model Regulation (NAIC #120). National model insurance regulation defining commercial plan coordination, subscriber vs. dependent rules, the dependent child Birthday Rule, and court decree priorities.

• TRICARE / Defense Health Agency. Have Other Health Insurance? Here’s How It Works With TRICARE. August 15, 2023 article: pharmacy other health insurance pays first; Medicaid, TRICARE supplemental plans, state crime-victim programs, and specified federal programs are billed to TRICARE first; the pharmacy other-health-insurance form is mailed to Express Scripts.

• X12. Claim Adjustment Reason Codes (X12). Official national standard code repository defining CARC 22 and related 835 claim adjustment reason codes.