## Integrated Pre-Authorisation

### Overview

The Integrated Pre-Authorisation feature allows merchants to pre-authorise funds on a customer’s card and manage that authorisation through the POS and Tyro EFTPOS terminal.

This feature is commonly used in scenarios such as hospitality tabs or delayed final charges, where a merchant wants to secure funds upfront and complete the transaction at a later time.

### A pre-authorisation follows this general lifecycle:

1. A pre-authorisation is opened with a specified limit.
2. The customer secures the pre-auth by tapping, swiping, or inserting their card.
3. The POS receives a completion reference.
4. The pre-auth can be increased, closed, or voided.


### How It Works

- The POS initiates a pre-authorisation request using the OpenPreAuth() function.
- The customer confirms the pre-auth on the Tyro terminal.
- Tyro Terminal Adapter (TTA) returns a response containing a Pre-Auth Completion Reference.
- The POS stores this reference and uses it for future actions on the pre-auth.


### Key Concepts

- Pre-Auth Limit: The maximum amount that can be charged.
- Completion Reference: A unique identifier required to manage the pre-auth.
- Incremental Updates: The pre-auth amount can be increased up to the original limit.


Pre-authorisations are automatically voided if they are not closed within 15 days.

Pre-auth completion and void operations do not require terminal interaction and can be processed while the terminal is disconnected or powered off.

### Supported Implementations

- TTA V2 supports:
- Event-based implementations
- Task-based (async) implementations
- Headful and Headless terminal adapters