Overview

One-Off payments represent the simplest transaction model supported by the SIBS Payment Gateway. In this model, a payment is executed as a single, self-contained transaction without any follow-up charging cycles or recurring billing.

The payment is initiated once by the merchant and completed once by the customer, with no reuse of credentials or scheduling of future charges.

This model is commonly used in standard checkout scenarios and serves as the foundation for most payment method integrations.

Within SPG, One-Off payments may be executed using different operational transaction types depending on the payment method and business scenario, including immediate purchase operations, authorization-based flows, and authorization followed by later capture.

The One-Off model therefore describes the transactional relationship itself rather than a specific authorization or settlement strategy.

What Is a One-Off Payment

A One-Off payment is a transaction where:

• The customer authorizes a payment once
• The payment corresponds to a single purchase or obligation
• No automatic future charges occur
• Each payment requires a new transaction initiation

From a technical perspective, every One-Off payment results in a unique transaction identifier and independent lifecycle.

The SPG transactionID should be treated as the authoritative identifier for transaction monitoring, webhook correlation, reconciliation, refund operations, and Status Inquiry requests throughout the payment lifecycle.

When to Use One-Off Payments

One-Off payments are appropriate when the transaction represents a discrete purchase or financial event.

Typical scenarios include:

• E-commerce purchases
• Ticketing and reservations
• Digital goods and downloads
• One-time invoices or bills
• Service payments and immediate settlement scenarios

They are not intended for recurring billing, subscriptions, or tokenized future payments.

Supported Payment Methods

Within the SIBS ecosystem, One-Off payments are supported across multiple payment methods, including:

• MB WAY
• Cards (Visa, Mastercard, etc.)
• Multibanco Reference

Each payment method may implement the One-Off model with different execution characteristics (immediate or near real-time vs asynchronous).

Execution Models

Although the conceptual model is simple, One-Off payments can behave differently depending on the payment method:

Immediate or Near Real-Time Payments

Payment outcome is typically confirmed during the checkout interaction or shortly afterwards through asynchronous transaction updates.

Examples:

• Cards (authorization or auth+capture)
• MB WAY

Characteristics:

• Immediate or near real-time transaction confirmation
• Synchronous or near real-time checkout experience

Asynchronous Payments

Payment completion occurs outside the checkout session.

Examples:

• Multibanco Reference

Characteristics:

• Delayed payment confirmation
• Requires final-state webhook notifications and, where needed, Status Inquiry for transaction monitoring and reconciliation
• Reference expiration handling

Transaction Lifecycle

The following diagram illustrates the generic operational lifecycle commonly followed by One-Off payment transactions in SPG.

Despite method-specific differences, One-Off payments generally follow a predictable lifecycle:

1. Transaction creation and payment initiation
2. Customer interaction or payment authorization
3. Processing by SPG and financial network partners
4. Transaction state progression using the external paymentStatus values exposed by SPG, such as Pending, Success, Declined, Error, or Timeout
5. Final transaction confirmation through synchronous response, final-state webhook notification, and/or Status Inquiry where operationally required

Depending on the payment method, the transition between steps may be synchronous or asynchronous.

For transaction lifecycle monitoring and Status Inquiry usage, refer to E.2 – Status Inquiry / Get Status.

For webhook delivery and asynchronous transaction notifications, refer to E.1 – Webhooks (Notifications).

Practical implementation examples, Postman collections, cURL examples, and sandbox testing scenarios are documented in F. Technical Examples and Best Practices.

Advantages of the One-Off Model

From a merchant and integration perspective, One-Off payments offer:

• Simple integration model
• Clear transaction boundaries
• No credential storage requirements
• Reduced operational complexity compared to recurring or credential-storage payment models
• Broad payment method compatibility

This makes them ideal as the first integration step for new merchants.

Particularities in the SIBS Context

When working with One-Off payments in SIBS SPG, several platform-specific aspects should be considered:

• Each payment produces a unique transaction in SPG
• Payment status may be delivered synchronously or asynchronously
• Webhook notifications should be implemented for asynchronous payment methods, with Status Inquiry used where needed for monitoring, recovery, or reconciliation
• Some methods support optional two-step processing (e.g., card pre-authorization)
• Settlement timing, reconciliation behavior, and financial processing flows may vary depending on the payment method and financial partner configuration

Understanding these aspects helps ensure correct handling of payment states across different methods.

One-Off vs Other Payment Models

To position One-Off payments within the broader ecosystem:

Model	Description
One-Off	Single, standalone payment
Recurring	Repeated merchant-initiated charges using stored authorization or payment credentials
Tokenized Payments	Payments executed using previously stored payment credentials, potentially supporting both One-Off and recurring transaction models
Pre-Authorization	Two-step operational variant where funds are authorized initially and captured later

This documentation section focuses exclusively on the One-Off model. Other models are covered in dedicated sections.

For recurring payment flows and Merchant Initiated Transactions (MIT), refer to D.2 – Recurring Payments.

For authorization and delayed capture flows, refer to D.3 – Two-Step Payments.

The Sandbox Payment Simulator may also be used to validate One-Off payment flows, customer interaction behavior, transaction lifecycle progression, and operational request/response payloads in a controlled sandbox environment.

Integration Context

In the SIBS Payment Gateway, One-Off payments can be implemented using multiple integration approaches:

• Hosted payment form (redirect or embedded)
• Server-to-server API integration
• Platform plugins for supported e-commerce platforms

Each approach exposes the same underlying transaction model while offering different levels of integration control.

Detailed implementation guidance for each payment method and integration approach is provided in the corresponding D.1.x payment method sections and in B. Integration Models.

Summary

One-Off payments form the baseline payment model in SIBS SPG, enabling merchants to process single, independent transactions across multiple payment methods.

By understanding the conceptual behavior and lifecycle of One-Off payments, integrators can more easily adopt the appropriate technical flow and payment method implementation.