# Processing payments as an SAP
The payment process is described in detail in [Payment Flow](/payment-processing/payment-flow-happy-path.md). This section will detail the specifics for the Source and Destination Settlement Access Providers.
## Role of SAPs in a specific Nexus payment
Nexus processes payments from the Source PSP to the Destination PSP via two Instant Payment Systems (IPSs). The Nexus payment is settled in each IPS between the respective PSP and SAP.
For a specific payment, a SAP will play one of two roles: as Source SAP, or as Destination SAP.
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In these examples, we assume that the FXP is not a member of either IPS and so uses both a Source SAP and a Destination SAP, as shown in the diagram below. See [Accessing Instant Payment Systems](/fx-provision/accessing-instant-payment-systems.md) for alternative scenarios where the FXP has IPS membership in one or both countries.
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An FXP that is not a participant in an IPS can make use of Settlement Access Providers
### When acting as Source SAP
The **Source Settlement Access Provider (S-SAP)** is a member of the Source IPS. It provides an account to the FXP, denominated in the Source currency.
* The Source PSP sends funds (in the Source Currency) to the FX Provider’s account at the S-SAP.
* This payment is processed through the Source IPS, which debits the Source PSP and credits the Source SAP.
* The Source SAP will in turn credit the FXP’s account.
The process flow for a Source SAP is almost equal to that of a regular Destination PSP, so **any PSP which is able to accept Nexus payments in the role of Destinatoin PSP should be able to perform the role of a Source Settlement Access Provider**, with minimal changes:
* The **S-SAP is not allowed to deduct any fees** from the amount transferred, while the D-PSP must deduct the Destination PSP fee.
* The S-SAP must credit the FXP with exactly the amount received from the S-PSP.
* For each specific `pacs.008` payment instruction, the S-SAP is able to recognize it acts as the S-SAP and not the D-PSP because the Nexus `pacs.008` references the S-SAP as the *Intermediary Agent 1,* while the D-PSP is referenced as Creditor Agent.
* Where an IPS uses a domestic message format that differs from the Nexus standard `pacs.008` payment instruction, an SAP must refer to the IPS’s documentation to understand how the SAP will be described in the message. The SAP must ensure it can distinguish between receiving a Nexus payment as S-SAP and receiving a payment as a D-PSP, and handle the payments accordingly.
* In the specific case the Source IPS is designed to use a [**4-leg settlement process**](/payment-processing/annex-4-step-vs-5-step-processes-in-domestic-clearing-and-settlement.md), when a payment is rejected in the D-IPS, the settlement will be reversed in the Source IPS.
* In this case, the S-SAP **must** reverse the credit on the FXP’s account. (Note that this requirement may already be in place for domestic payments.)
* This does not apply to a [5-leg settlement process](/payment-processing/annex-4-step-vs-5-step-processes-in-domestic-clearing-and-settlement.md), as in this case the Source SAP will not credit the FXP’s account until the settlement confirmation is received from the Destination IPS.
Similarities and Differences Between S-SAP and D-PSP
Source SAP
Destination PSP
Settlement
S-SAP is credited in the local settlement cycle
Must be able to confirm or reject ALL incoming payments in real-time.
In the case that the local IPS uses a 4-step settlement process in the local IPS, the S-SAP must be able to reverse the credit on the FXP’s account in case of a reject from the D-IPS.
D-PSP is credited in the local settlement cycle.
Agent in the Nexus pacs.008 payment instruction
Intermediary Agent 1
Creditor Agent
Fees
S-SAP must not make any deductions from the payment amount. Any fees to the FXP must be invoiced to the FXP separately.
D-PSP must deduct the Destination PSP fee before crediting the Creditor Account
## When acting as Destination SAP
The **Destination Settlement Access Provider (D-SAP)** is a member of the Destination IPS. It provides an account to the FXP (or Source PSP in cases where the PSP wishes to manage their own FX) denominated in the Destination currency.
* The D-SAP will debit the FXP’s account at the D-SAP upon receiving the payment instruction from Nexus
* The D-SAP will then send funds (in the Destination Currency) to the Destination PSP’s account
* This payment is processed through the Destination IPS, who debits the D-SAP and credits the D-PSP
The process flow for a Destination SAP is almost equal to that of a Source PSP. In both cases, a payment instruction is to be validated and debited; in the case of the S-PSP the value is debited from the Sender (Debtor); in the case of the D-SAP the value is debited from the account of the FXP. **A PSP able to initiate Nexus payments would be able to perform the role of a D-SAP**, with minimal changes:
* **The D-SAP must apply any fees to the payment amount.**
* The D-SAP must debit the FXP exactly the amount to be transferred (without adding fees).
* The D-SAP must transfer the full amount (as defined in the Interbank Settlement Amount field) to the D-PSP, without deductions.
* The D-SAP may charge the FXP a separate transaction fee, according to their bilateral agreement.
* In the Nexus message implementation, the D-SAP is identified as the Intermediary Agent.
* Where an IPS uses a domestic message format that differs from the Nexus standard `pacs.008` payment instruction, the SAP must refer to the IPS’s documentation to understand how it (the SAP) will be described in the message.
* A D-SAP will receive the Nexus payment instruction from the D-IPS instead of via its own mobile app or internet banking channels (as would be the case for the S-PSP). The message may be `pacs.008` message, depending on the local IPS implementation of Nexus. (See [How the Destination IPS initiates the payment via the Destination SAP](/settlement-access-provision/processing-payments-as-an-sap/how-the-destination-ips-initiates-the-payment-via-the-destination-sap.md) for further details.)
| **Similarities and Differences Between Destination SAP and Source PSP** | **Source PSP** | **Destination SAP** |
| ----------------------------------------------------------------------- | ------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Settlement** | Debits the Sender before submitting the payment instruction to the S-IPS. |
Receives instruction to debit FXP’s account via Nexus/D-IPS.
The message used for payment initiation can either be a Nexus pacs.008 message or a local format (depending on the local Nexus implementation).
D-SAP instructs D-IPS to credit the D-PSP.
|
| **Agent in the Nexus `pacs.008` payment instruction** | Debtor Agent | Intermediary Agent |
| **Fees** | Has specific rules around handling and disclosing fees. | Must not deduct fees from the value being transferred. |
{% hint style="info" %}
The role of a D-SAP is also very comparable to PSPs providing sponsored access to indirect participants or EMIs. In that case, the PSP processes payments on behalf of the indirect participant or EMI; in the Nexus case, the SAP processes the payment on behalf of the FXP. **PSPs who provide sponsored access should be able to act as a D-SAP with minimal to no change** (depending on the local setup of the IPS involved).
{% endhint %}
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