It defines how institutions must investigate, communicate, decide, and execute refunds under a mandatory and standardized process enforced by the Central Bank of Brazil (BACEN). MED ensures consumer protection, consistency across institutions, and full auditability within the Pix ecosystem.

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When MED applies

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A Pix transaction enters the MED process when a financial institution identifies the need for formal, regulated investigation, typically in cases such as:

• Fraud (phishing, account takeover, social engineering)
• Unauthorized transactions (user did not approve the payment)
• Operational errors (duplicate sends, incorrect recipient, wrong value)
• System or processing failures causing financial impact

MED runs independent of standard Pix refund flows. Standard refunds are voluntary; MED is mandatory and regulated.

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Regulatory MED lifecycle

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Every MED case follows a strict set of states defined by BACEN. Institutions must comply with the deadlines and response requirements at each stage.

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Lifecycle overview

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Valid reasons for MED disputes

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A MED case must be opened under one of the regulated dispute categories: Each case must include justification and supporting evidence aligned to BACEN’s requirements.

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Possible outcomes

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Approved cases trigger a pacs.004 message for refund execution through SPI.

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MED process — step-by-step flow

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Below is the regulated MED process followed by all Pix institutions:

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1. Validation

• Transaction exists and is in COMPLETED state
• Transaction age ≤ 30 days
• Minimum value R$ 1,00
• No existing open MED case for the same transaction

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2. Evidence collection

• Fraud markers from DICT
• Internal risk analysis
• Upload of evidence (documents, screenshots, logs)
• Compliance verification

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3. Case creation

• MED ID assigned
• Regulatory deadlines computed (7 / 10 days)
• Notifications sent to involved institutions
• Timeline and audit trail started

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4. Analysis phase

• Examination of submitted evidence
• Evaluation of counterpart’s response
• Application of internal and regulatory rules

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5. Decision

• Refund executed via pacs.004 (if approved)
• Ledger postings applied (debit/credit)
• Institutions notified
• All events logged for audit

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6. Completion

• Case moves to COMPLETED, REJECTED, or EXPIRED
• 90-day retention period begins
• Evidence archived and audit trail locked

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Integration points

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Although MED is a regulatory process, it interacts with core Pix components:

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Compliance expectations

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Institutions must ensure:

• Enforcement of all regulatory deadlines
• Cryptographic protection of evidence files
• Full audit trail including timestamps and event logs
• Standardized MED communication with counterpart institutions
• SLA monitoring and status tracking
• Consistent customer notification logic
• Proper use of dispute categories and reason codes

These controls guarantee system-wide integrity and consumer protection.

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Relationship with refunds and reversals

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While refunds and reversals are standard Pix operations, MED is the regulated mechanism used when:

• The refund is tied to fraud or unauthorized activity
• The originating institution disputes the transaction
• Additional evidence and regulated communication is required

In these cases, the refund is executed through the MED decision, not as a voluntary action.