curl https://production.methodfi.com/payments \
  -X POST \
  -H "Method-Version: 2025-07-04" \
  -H "Authorization: Bearer sk_WyZEWVfTcH7GqmPzUPk65Vjc" \
  -H "Idempotency-Key: 24c47283-0cc8-43a0-8b4a-ce16d002de97" \
  -H "Content-Type: application/json" \
  -d '{
    "amount": 5000,
    "source": "acc_JMJZT6r7iHi8e",
    "destination": "acc_AXthnzpBnxxWP",
    "description": "Loan Pmt"
  }'

{
  "error": {
    "type": "API_ERROR",
    "code": 503,
    "sub_type": "IDEMPOTENCY_UNAVAILABLE",
    "message": "Idempotent requests are temporarily unavailable. To ensure idempotency try your request later, or fall back to a non-idempotent request."
  }
}
Method’s API supports idempotency for safely retrying requests without accidentally performing the same operation twice. This helps avoid unwanted duplication in case of failures and retries. For example, in the case of a timeout error, it is possible to safely retry sending the same API payment call multiple times with the guarantee that the payment will only be created once. Method’s idempotency works by saving the resulting status code and body of the first request made for any given idempotency key, regardless of whether it succeeded or failed. Subsequent requests with the same key return the same result, including 500 errors.

​
Enable idempotency

To submit a request for idempotent processing, send a request with the Idempotency-Key: <key> header. The <key> can be any unique string up to 255 characters long. (We recommend using V4 UUIDs). All POST requests accept idempotency keys.

​
Idempotency error

In the unlikely event that the idempotent data store is unavailable, the API returns a 503 error status with the a sub type of IDEMPOTENCY_UNAVAILABLE If idempotency is required, we recommend retrying your request later, otherwise, fall back to non-idempotent processing by not submitting the Idempotency-Key header. 
curl https://production.methodfi.com/payments \
  -X POST \
  -H "Method-Version: 2025-07-04" \
  -H "Authorization: Bearer sk_WyZEWVfTcH7GqmPzUPk65Vjc" \
  -H "Idempotency-Key: 24c47283-0cc8-43a0-8b4a-ce16d002de97" \
  -H "Content-Type: application/json" \
  -d '{
    "amount": 5000,
    "source": "acc_JMJZT6r7iHi8e",
    "destination": "acc_AXthnzpBnxxWP",
    "description": "Loan Pmt"
  }'

{
  "error": {
    "type": "API_ERROR",
    "code": 503,
    "sub_type": "IDEMPOTENCY_UNAVAILABLE",
    "message": "Idempotent requests are temporarily unavailable. To ensure idempotency try your request later, or fall back to a non-idempotent request."
  }
}