Skip to main content

Documentation Index

Fetch the complete documentation index at: https://developers.circle.com/llms.txt

Use this file to discover all available pages before exploring further.

This how-to shows you how to retrieve the remaining Fast Transfer allowance using the CCTP API. The Fast Transfer allowance is Circle’s mechanism for backing faster-than-finality USDC transfers before burns reach hard finality on source chains.

​
Prerequisites

Before you begin, ensure you have:
  • Installed cURL on your development machine

​
Get the Fast Transfer allowance

Call the GET /v2/fastBurn/USDC/allowance endpoint to retrieve the current remaining Fast Transfer allowance. Example request
Shell
curl --request GET \
  --url 'https://iris-api-sandbox.circle.com/v2/fastBurn/USDC/allowance' \
  --header 'Accept: application/json'
Response 
{ "allowance": 99999999225.24174, "lastUpdated": "2025-12-02T13:17:02.453Z" }
The response includes:
  • allowance: The remaining Fast Transfer allowance in USDC units
  • lastUpdated: The UTC timestamp when the allowance was last updated
Fast Transfer allowance details:
  • The allowance represents the total value of USDC that can be minted through Fast Transfer before related burns on source chains reach hard finality.
  • When you initiate a Fast Transfer, the burn amount temporarily debits the allowance.
  • Once the burn reaches finality on the source chain, the corresponding amount is credited back to the allowance.
  • If the allowance is insufficient for your transfer, you should either wait for the allowance to replenish or use Standard Transfer instead.