CMS Pub. 100-05, ch. 5, § 40.7.1

Expenses paid by the GHP count toward the Medicare deductible. For claims where

reasonable charge applies, the A/B MAC (Part B) and DME MAC credits the payment

made under the insurer's plan toward the Medicare deductible up to the amount of the

Medicare reasonable charge or fee amount for the service; i.e., if the primary plan paid

$75 on a procedure and the reasonable charge or fee amount for the procedure is $50,

the A/B MAC (Part B) and DME MAC credits $50 toward the deductible.

The A/B MAC (Part B) and DME MAC processes all claims to CWF, including those to

be denied because the claim has not been submitted to the primary payer, if the Medicare

deductible is unmet. If the beneficiary has GHP, and it is not reflected in the CWF

response, the A/B MAC (Part B) either updates the MSP auxiliary file with an "I"

indicator if it is sure of the MSP involvement (see §10.1 subsection 2), or if further

development is required, advises the MSP Contractor via ECRS, and pends the claim

awaiting the MSP Contractor results via CWF (See §10.2.1, above). DME MACs do not

create “I” records. In these situations, the DME MAC submits an ECRS Inquiry to the

MSP Contractor.