# Replacing a Lost Primary Account Number (PAN)
source: https://developer.mastercard.com/account-catalog-services/documentation/use-cases/pan-registration/lost_stolen_request/index.md

When a Primary Account Number (PAN) is lost or compromised, an immediate action is essential to protect one's financial assets. This service provides a PAN replacement service can securely register a new account number, ensuring continuous access to financial services without interruption and their financial information remains secure and accessible.

#### Following are the execution steps: {#following-are-the-execution-steps}

1. The customer provides a PAN with replaced PAN to provide lost or replacement information of PAN in Account Catalog Services (ACS) format through the API.
2. The ALM validates the PAN, replaced PAN and its attributes, then updates the lost information of the PAN accordingly.
3. The API response is provided to customers with a registered account category code, accept codes or reject codes as applicable.
4. If the customer has opted for a detailed response, Mastercard sends the detailed response to the customer on its configured API URL.

## Sequence Diagram {#sequence-diagram}

Diagram lost_stolen_pan