Construct the $member-match Parameters resource with the MemberPatient parameter (Patient demographic data) and the CoverageToMatch parameter (old payer coverage details)
POST the Parameters to the new payer's Patient/$member-match endpoint using SMART Backend Services credentials
Parse the response Parameters resource to extract the matched member identifier returned by the new payer
Use the matched identifier to request the member's prior coverage data via the PDex member history operation
Store the matched identifier for subsequent data retrieval requests within the payer-to-payer exchange flow
Known gotchas
$member-match is defined on the Patient resource type endpoint, not on a specific Patient instance; posting to a patient instance URL is incorrect
The operation may return HTTP 422 if the member cannot be uniquely matched; implement handling for both no-match and multiple-match error conditions described in the OperationOutcome
CoverageToMatch must include the subscriberId as it appeared on the prior plan; mismatched formatting (leading zeros, hyphens) frequently causes match failures
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