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Prepare and Submit an MSP Claim

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Step 1: Determine if an MSP Claim Must be Submitted to Medicare

Before you can bill Medicare, you are first required to bill the payer you have identified as primary for the beneficiary’s services. Refer to “Determine if Medicare is Primary or Secondary for a Beneficiary’s Services.”

Once you bill and receive payment from the primary payer for the beneficiary’s services, use the following guidelines to determine whether or not to submit a MSP claim to Medicare:

  1. Primary payer partially paid ‑ If the primary payer made payment greater than zero but less than full payment, you are required to submit an MSP claim (known as an MSP partial-payment claim). The receipt of less than full payment may be due to a variety of other reasons such as the primary payer’s application of a deductible, coinsurance, or co-payment.
  2. Primary payer fully paid ‑ For Medicare Part B services, providers are strongly encouraged to submit an MSP claim when the primary payer has made full payment.

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Step 2: Check Medicare’s Eligibility Files via NGSConnex to Determine if There's Other Insurance Primary to Medicare

Submit claim based information obtained via Model Admission Questions to Ask Medicare Beneficiaries.

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Step 3: Prepare the MSP (Partial-Payment or Full-Payment) Claim

To prepare the MSP claim, use the following guidelines:

  1. Complete the claim form CMS-1500 or electronic equivalent in the usual manner.
  2. Report all claim coding usually required for the services including charges for all Medicare-covered services, not just the balance remaining after the primary payer’s payment.
  3. Report the covered and noncovered charges as usual. Do not report the charges paid for by the primary payer as noncovered.
  4. If Medicare is the tertiary payer, refer to “Prepare and Submit a Medicare Tertiary Claim” for instructions.
  5. In addition to all required Medicare coding, the following fields are required to be completed for MSP claims. Paper claim form Items are listed below; refer to the National Uniform Claim Committee 1500 Claim Form Map to the X12N Health Care Claim: Professional (837) for their electronic equivalents.
CMS-1500 Item Instructions
Item 4 Indicate the name of the insured for the insurance that is primary to Medicare (may or may not be the patient). If the insured and the patient are same, enter “SAME” in this field.
Item 6 Check the appropriate box for the patient’s relationship to the insured (self, spouse, child, other).
Item 7 Enter the insured’s address and telephone number. When this address is the same as the patient’s, enter “SAME” in this field.
Item 8 This field is reserved for NUCC use.
Items 10a‑10c Indicate “yes” or “no” for “Is patient’s condition related to…” questions (employment, auto accident, other accident). If the patient’s condition is related to an auto accident, include the two digit state code (official US Postal abbreviation) under Place.
Item 11 Enter the insured’s policy or group number.
Item 11a Enter the insured’s eight-digit birth date (MMDDYYYY format) and gender (sex) if different from information listed in Item 3.
Item 11b Leave blank. Not required by Medicare.
Item 11c If Medicare is the secondary payer, complete this line item.
Item 11d Not required by Medicare; do not complete this Item for MSP billing.


For electronic claims, additional information is needed to be submitted on the claim. This is the same information that would appear on the primary insurer’s EOB. Since electronic MSP claims are not submitted with an EOB, you need to ensure that the following information is included on your electronic claim submission:

  • Patient name
  • Date of service
  • Insurance company name
  • Procedure code or billed amount per claim line or entire claim (must match Medicare claim)
  • Payment amount
  • Reason code for no payment for a line item with the definition of the reason code on the primary EOB

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Step 4: Submit the MSP Claim to Medicare for the Beneficiary

Once the MSP claim is properly prepared, submit the MSP claim to Medicare for processing. Providers must submit claims to Medicare on behalf of the beneficiary; you cannot require that the patient submit the claim to Medicare.

MSP claims must be submitted to Medicare in the same format that you submit all of your other claims to Medicare. It is not an acceptable practice to “drop to paper” for MSP claims if you submit all of your other Medicare claims electronically. However, if you have an approved ASCA waiver, you may submit MSP claims in hard-copy format, using the most current version of the CMS-1500 paper claim form. When using the CMS-1500 paper claim form, only original forms printed in red drop-out ink are accepted (no photocopies).

For hard-copy claim submissions, you must properly code the MSP claim on a hardcopy CMS-1500 claim form, attach any supporting documentation such as the primary payer’s remittance and/or EOB statement and submit it to the proper National Government Services Claims P.O. Box, depending on the state in which your practice/office is located.

MSP claims must be submitted to Medicare within the established timely filing guideline for all Medicare claims, which is one calendar year from the date of service. There are some exceptions to the timely filing limit, but none of those exceptions apply to determining a patient’s MSP status. As always, any claims that are not submitted within the time limit are provider-liable and the beneficiary cannot be charged.

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Medicare’s Processing of MSP Claims

  • Claim accepted: If MSP claims are submitted in accordance with the above instructions and do not encounter any other editing, they will proceed to the payment floor.
  • Claim rejected/returned to provider: If MSP claims fail to meet Medicare’s usual claim submission requirements and/or fail to meet the requirements for MSP billing, they will not be accepted and you must resubmit the claims correctly.

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Revised 11/8/2024