Errors

What can go wrong, and whether it costs you anything.

Errors come back with "success": false and a human-readable message. Billing errors from the check endpoints also carry a code:

JSON

{
  "success": false,
  "code": "INSUFFICIENT_CREDITS",
  "message": "Account balance is too low for this check.",
  "requestId": "REQ-1791820800000",
  "timestamp": "2026-10-12T10:00:00.000Z"
}

Status	When	Billed	What to do
`400`	Missing or invalid field ("Validation error", with an errors array), or an unknown bankCode.	No	Fix the request. The errors array names each bad field.
`401`	No Authorization header, a malformed token, or an expired or revoked key.	No	Check the token is Base64 of clientId:clientSecret and the key is active.
`403`	"Insufficient permissions. Required: identity.write" (or identity.read).	No	Add the Identity scope to the key under Settings → Developers.
`403 INSUFFICIENT_CREDITS`	Your wallet balance is lower than the price of the check.	No	Top up your wallet, then retry.
`404`	Check or session not found (or it belongs to another account).	No	Check the ID, and that you're using the right account's key.
`429`	Too many requests in a short period.	No	Back off and retry.
`502 PROVIDER_ERROR`	The register didn't answer (timeout or outage).	Refunded	Retry after a short wait. The charge is returned to your wallet automatically.
`500`	Unexpected error on our side.	No	Retry; contact support with the time of the request if it persists.

A "no match" isn't an error

When the details don't match the register, you get 200 with "isValid": false (or null if the register couldn't decide). The check ran, so it's billed. Only treat "isValid": true as verified.