CAID
What is CAID?
Card Acceptor ID (CAID) is an alphanumeric string that identifies a specific store location or transaction point within a merchant's acquiring relationship. It is a unique identifier for the origin of a payment transaction, provided by the merchant's , and its value typically ranges from 1 to 15 characters long.
The CAID's job is to route, match, and reconcile transactions across acquirers and card networks. When a transaction is initiated, the CAID is sent to the relevant card network and passed on to the acquiring bank to identify the origin point. It pins down the exact place a payment came from, so funds settle to the correct . The CAID is also required in every subsequent message tied to the original , including reversals, disputes, and dispute responses.
Key facts
- Stands for: Card Acceptor ID, also referred to as Card Acceptor Identifier
- Format: alphanumeric string, typically 1 to 15 characters
- Assigned by: the merchant's acquiring bank
- Scope: identifies a single transaction point – a store location, a payment terminal, or a checkout integration
- Lifecycle: travels with every message in the transaction, from authorization through clearing, reversals, and chargebacks
CAID vs MID
CAIDs are regularly confused with (MIDs), and the two often appear side by side in acquirer reports and chargeback paperwork. They identify different things:
| Identifier | What it identifies | Scope |
| CAID | The specific transaction point – a store, terminal, or checkout integration | One per acceptance point under a merchant |
| MID | The merchant itself in the acquirer's system | One per merchant, can group multiple CAIDs |
A single merchant can have one MID covering several CAIDs – one CAID per physical store, e-commerce site, or terminal under that MID. Acquirers and card networks use both together to reach the right merchant and the right acceptance point.
Why it matters
The CAID is how the and the acquirer agree on which acceptance point a transaction came from. Its accuracy directly affects three things:
- Settlement routing. Funds settle to the merchant account tied to the CAID. A wrong or missing CAID lands money in the wrong account or stalls settlement.
- Dispute handling. When a is filed, the acquirer uses the CAID on the original authorization to pull the right transaction record and route the dispute back to the right acceptance point.
- Risk monitoring. Card networks track fraud and chargeback rates per CAID, not only per merchant. A single bad store location can trigger acquirer review even when the merchant's overall ratios look healthy.
Where to find it
- Merchant: the CAID appears in the acquirer or PSP dashboard against each acceptance point, and in batch and chargeback reports alongside the transaction reference.
- Cardholder: the CAID isn't visible on a cardholder statement. The on the statement points back to the merchant, not the specific CAID, so tracing a charge to its acceptance point goes through the merchant.
- Developer: the CAID is carried in the authorization message; where a PSP exposes it, it appears on the transaction record in API responses or webhook payloads, alongside the MID and terminal ID.
