Real-time payments: the technological challenges behind instant settlement.

The experience of making an instant payment seems simple: enter the details, confirm the operation, and receive a response in a few seconds. Behind the scenes, however, this speed relies on an infrastructure capable of validating information, applying security rules, moving resources, updating balances, and recording each step without interruptions or duplications.

Scale helps to frame the challenge. According to the Pix Management Report 2023–2025, from the Central Bank, Pix reached nearly 80 billion transactions in 2025, a growth of 25.7% compared to the previous year. The financial volume grew by 33.8% and surpassed R$ 35 trillion. On December 5, 2025, the system recorded a record of 313.3 million transactions in a single day.

This volume changes the role of technology in financial institutions. In a batch-based model, failures can be analyzed and corrected before the next processing cycle. In real-time, each transaction must be treated as an individual event, with immediate validation, response, and recording. There is no room to rely on manual checks, overnight processing, or integrations that take hours to update information.

Therefore, offering instant payments does not just mean speeding up an existing infrastructure. The institution needs to automate the end-to-end flow, ensure idempotency, handle distributed failures, and reconcile large volumes in a few seconds. It must also integrate the payment network with accounting, financial, anti-fraud, and customer service systems without losing traceability.

The central challenge is not just to make payments arrive faster. It is to build an architecture capable of maintaining consistency, security, and availability while thousands of events are processed simultaneously — even when some component of the operation does not respond as expected.

What technically changes between batch settlement and instant settlement?

In batch settlement, transactions are accumulated and processed at defined times. This interval allows for consolidating files, executing validations, correcting inconsistencies, and calculating positions before financial movement.

In instant settlement, each payment must be processed individually, in a few seconds, and with an immediate response. The platform must check balances, limits, recipient data, anti-fraud rules, and participant availability during the transaction itself.

This change requires continuously available infrastructure, including outside business hours. It also reduces the margin for manual interventions: controls that could previously be executed between two cycles must now occur automatically and in real-time.

Another challenge is scale. An architecture prepared for daily averages may not support peaks concentrated in a few minutes. Therefore, elastic capacity, monitoring, and load testing become essential.

What is STP and why is it a prerequisite?

STP, or straight-through processing, is the processing of a transaction end-to-end without manual intervention. From initiation to confirmation, systems exchange information and execute steps automatically.

In an STP flow, the platform must:

• validate data and business rules;
• check limits and resource availability;
• apply security controls and fraud prevention;
• forward the instruction to the network;
• receive and interpret the response;
• update balances and records;
• communicate the result to the involved systems.

STP is a prerequisite because instant payments do not accommodate manual approvals or file transfers between areas. If a step depends on human checks, the flow fails to operate in the required time.

Automation, however, must include the handling of exceptions. Transactions that fall outside the norm should be sent to an analysis queue without blocking the processing of others.

How to ensure idempotency and avoid duplication in instant payments?

In distributed systems, a message can be resent when confirmation is delayed or a connection is interrupted. Without adequate controls, the platform may interpret the repetition as a new order and process the same payment multiple times.

Idempotency ensures that multiple requests related to the same operation produce a single financial effect. For this, each payment must receive a unique key, used in all steps of the flow.

Before executing an instruction, the system checks whether that key has already been processed. If it finds a completed operation, it returns the recorded result instead of moving the resources again. If the transaction is still in progress, it prevents concurrent processing until its state is defined.

This control must be combined with persistent records, uniqueness constraints, state change history, and secure retry policies. Simply checking if two messages have similar content is not enough to prevent duplications.

What happens when a transaction fails in the middle of settlement?

A failure should not automatically turn the transaction into a success or cancellation. In some cases, the institution sends the instruction but does not receive the response due to a network interruption. The payment may have been settled even if the originating system has not yet received confirmation.

Therefore, each operation needs to follow a state machine, with situations such as:

• received;
• in validation;
• authorized;
• sent for settlement;
• settled;
• rejected;
• under review;
• reverted.

When in doubt, the platform should check the operation’s state before attempting to process it again. Automatic retries must respect limits, intervals, and idempotency rules.

In distributed flows, compensatory transactions may also be used. If a subsequent step fails, a new operation undoes or neutralizes the previous effects in a traceable manner. The original history must be preserved, avoiding changes that eliminate evidence of what occurred.

Internal validation quote suggestion: “Real-time payments do not depend solely on speed. They require an architecture prepared to make decisions, record events, and respond to failures at the same pace that transactions occur.” — João Paulo Miranda, CEO of Objective

How does an event-driven architecture support real-time payments?

In an event-driven architecture, each relevant change is published so that other components can react. Events such as “payment received,” “analysis approved,” or “settlement confirmed” trigger the next steps without requiring one system to control the entire flow in a centralized manner.

This model reduces coupling between the payment platform and systems such as anti-fraud, accounting, notifications, customer service and reconciliation. Each component can consume the necessary events and evolve with greater independence.

The architecture also favors scale and resilience. Messages can be distributed among different consumers, while queues absorb temporary peaks without discarding transactions.

For it to work securely, however, the model requires governance. Events need to have defined contracts and versions, unique identification, ordering when necessary, and mechanisms to deal with messages that could not be processed. Monitoring the entire transaction path is also essential for locating failures in distributed environments.

How to reconcile transactions that settle in seconds?

Reconciliation does not disappear with instant settlement. It also needs to become continuous. Instead of comparing files only at the end of the day, the institution tracks each state change and verifies whether internal records correspond to confirmations received from the payment infrastructure.

Each transaction should have identifiers that allow relating:

• the client’s request;
• the order sent;
• the network response;
• the financial movement;
• the accounting entry;
• any potential return or reversal.

Discrepancies must be identified quickly and sent for resolution according to their criticality. An external confirmation without updating the internal balance, for example, requires a different priority than a temporary failure in sending a notification.

It is also advisable to maintain periodic closures to verify the global integrity of positions. The difference is that they cease to be the first moment a problem appears and serve as an additional layer of control.

Where to start preparing a legacy platform for real-time?

The first step is to map the complete payment flow, from initiation to accounting. The institution must identify file integrations, manual activities, batch processing, undocumented rules, and components that do not support continuous operation.

With this diagnosis, the evolution can start with the capabilities that enable subsequent stages:

• create a unique identifier for each transaction;
• define states and transitions of the payment;
• expose legacy functions through APIs;
• automate validations and tests;
• implement end-to-end monitoring and tracking;
• replace batch integrations with events where beneficial;
• test volume, downtime, and recovery;
• migrate components in controlled waves.

It is not necessary to rewrite the entire platform before achieving results. An integration layer can shield the legacy while new services take on specific functions, such as validation, notifications, or reconciliation. The old components are gradually replaced, with defined performance and security criteria for each step.

The case of the multinational insurance company served by Objective helps illustrate this path. The evolution of the platform incorporated payments via Pix and credit card and involved financial, accounting, billing, and collection modules. The project shows that adding a new payment method is not an isolated change: it requires integration between different processes and systems of the operation.

Preparing a platform for real-time payments is, therefore, a transformation of architecture and processes. STP, idempotency, events, error handling, and continuous reconciliation must work as parts of the same design so that speed is not achieved at the expense of control or reliability.

Does your company need to evolve financial systems to securely, scalably, and reliably process instant payments? Get in touch with the specialists at Objective and discover how to prepare your architecture for this transformation.

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