# Linking
source: https://developer.mastercard.com/mastercard-supplier-payment-agent/documentation/use_cases/business-payment-service/linking/index.md

## How linking works {#how-linking-works}

Linking allows trading partners to establish relationships in Business Payment Service, further ensuring the right Suppliers get paid. An approved link between trading partners reduces the probability that a payment instruction fails during the lifecycle of the payment instruction due to incorrect Supplier or Supplier Payment Agent data. By sending a link request, Supplier Payment Agents are able to approve that the given Buyer is a customer of their Supplier and should be able to pay the Supplier. To integrate with the linking APIs, refer to the [linking tutorial](https://developer.mastercard.com/mastercard-supplier-payment-agent/tutorial/linking/index.md).
Diagram linking2

The linking overview diagram displays the main steps for the linking process.
Note: With the April 2023 release, the previously required `supplierRegistrationId` field is now optional.   
Additionally with the April 2023 release, an approved linking request is required when the Supplier payment preference flag is set to `NO`. The flag default state is set to `NO`. If the display options for Supplier payment preferences are set to `YES`, then the available Supplier payment preferences are displayed. Payment Preferences are only exposed to Buyer Payment Agents to send electronic card spend to Suppliers. These Buyer Payment Agents must be a part of the Track BPS network.Contact your Mastercard representative to set the Supplier payment preferences flag.

**Step 1**: Supplier Payment Agent Sends nudge linking request.

**Step 2** : Buyer Payment Agent initiates the linking request by calling the POST linking API.   

**Step 3** : Business Payment Service notifies the Supplier Payment Agent of the linking request.   

**Step 4** : Supplier Payment Agent either accepts or rejects the linking request.   

**Step 5** : Business Payment Service notifies the Buyer Payment Agent of the approval.   
**NOTE: If the linking request is rejected, the process ends once the Buyer Payment Agent receives the even notification with the linking rejection.**

**Step 6**: Business Payment Service notifies the Buyer Payment Agent if the Supplier has any Supplier payment preferences in place.

**Step 7 - optional** : Supplier Payment Agent submits the delete linking request by calling the DELETE linking API.   

**Step 8 and 9**: Business Payment Service notifies both the Buyer Payment Agent and the Supplier Payment Agents of the link removal.

**Step 10 - optional**: Supplier Payment Agent submits the search and filter link request by calling the GET linking API.

**Step 11**: Business Payment Service returns linking information.

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## Linking nudge request {#linking-nudge-request}

Note: If a Supplier Payment Agent nudges a Buyer Payment Agent with a linking request, the Buyer Payment agent receives the SUPPLIER_SUGGESTING_LINK_REQUEST event notification. The Buyer Payment Agent can respond to the nudge request by initiating a link. However, the Buyer Payment Agent can initiate a linking request without a nudge from the Supplier Payment Agent.

![alt text](https://static.developer.mastercard.com/content/mastercard-supplier-payment-agent/uploads/suggestlink.png)
Note: The Mastercard assigned ICA is used for agent identification in all service requests for core operations. A customer service provider can use their API credentials to transact on behalf of a customer by providing their customer's ICA number in the request. Direct payment agents can still transact by entering their own ICA when sending a transaction to Mastercard Track Business Payment Service.
API Reference: `POST /supplier-payment-agents/{ica}/supplier-payment-profiles/{spa_profile}/suggested-buyer-links`

## Updating a link request with authorization status {#updating-a-link-request-with-authorization-status}

![alt text](https://static.developer.mastercard.com/content/mastercard-supplier-payment-agent/uploads/updatelink.png)

API Reference: `PUT /supplier-payment-agents/{ica}/supplier-payment-profiles/{spa_profile}/buyer-links/{bpa_profile}`


API Reference: `PUT /supplier-payment-agents/{ica}/buyer-links`

## Send locally stored payment preferences directly to a linked Buyer {#send-locally-stored-payment-preferences-directly-to-a-linked-buyer}

![alt text](https://static.developer.mastercard.com/content/mastercard-supplier-payment-agent/uploads/external-preferences.png)

API Reference: `PUT /supplier-payment-agents/{ica}/supplier-payment-profiles/{spa_profile}/buyer-links/{bpa_profile}/payment-preferences`

## Delete an existing link {#delete-an-existing-link}

![alt text](https://static.developer.mastercard.com/content/mastercard-supplier-payment-agent/uploads/deletelink.png)
Note: If a Buyer or Supplier Payment Agent deletes a link, both agents receive the LINK_REMOVED event notification.
API Reference: `DELETE /supplier-payment-agents/{ica}/supplier-payment-profiles/{spa_profile}/buyer-links/{bpa_profile}`

## Search for an approved link {#search-for-an-approved-link}

![alt text](https://static.developer.mastercard.com/content/mastercard-supplier-payment-agent/uploads/getlink.png)

API Reference: `GET /supplier-payment-agents/{ica}/buyer-supplier-links`