Getnet DocsGetnet Docs

Interest Calculation Strategy

View as MarkdownView this page as plain textOpen in ChatGPTAsk questions about this pageOpen in ClaudeAsk questions about this pageOpen in PerplexityAsk questions about this page
Connect to CursorUse these docs in CursorConnect to VS CodeUse these docs in VS Code

When processing installment transactions, Getnet App2App offers two distinct strategies to handle interest and installment values. This choice is defined by the operationMode parameter and dictates whether the terminal or your application is responsible for the financial logic.

The operationMode parameter must be sent as part of the Request Deeplink for Payment operations. It defines which system is responsible for the installment interest logic.

See below how the operationMode parameter determines the transaction:

ValueModeDescription
0ManualDefault. The terminal calculates the final transaction values based on internal business rules. This mode is automatically assumed if the parameter is not sent.
1CalculatedThe third-party application is responsible for all financial calculations. The terminal processes the final amount received without any modifications.

If the operationMode is not sent, the terminal will default to manual mode (0), meaning it will perform its own calculations based on internal business rules and user selections.

Transaction response data

Regardless of the mode used (Manual or Calculated), the response objects for Payment and Refund operations will always include the following fields:

  • The final charged amount
  • The paymentType indicating the payment method (e.g., credit, debit)
  • The installments parameter, indicating the number of installments used
  • Other relevant fields describing the confirmed payment conditions

Credit card transactions

When a credit card is detected, the terminal performs a request to the Tax Engine (the central service responsible for validating the merchant’s authorized financial configurations). This engine ensures that the requested installment plans and interest settings align with the merchant’s commercial agreement.

The Tax Engine is Getnet’s fiscal and financial rules engine. It acts as a real-time validator that verifies which installment conditions and interest rates a merchant is authorized to offer. When the terminal detects a credit card, it queries this engine to ensure the transaction complies with the merchant’s commercial agreements.

The terminal’s behavior depends on the installment data you send:

  1. If no installment data is sent, the terminal redirects the user to manually select the installment plan and number of installments on the device.

  2. If the installment data differs from the Tax Engine response, the payment will allow the user to select an option different from the one received, as the requested conditions are not authorized by the establishment.

  3. If the sent data matches the Tax Engine exactly, the terminal skips plan selection and goes straight to the payment confirmation screen.