Terminal ID number
What is a terminal ID number?
A terminal ID number (TID) is a unique eight-digit alphanumeric code that identifies a specific point-of-sale terminal or payment device. Payment processors assign a TID to each terminal so every transaction can be traced back to the exact device that handled it, which helps merchants, banks, and card networks keep accurate records.
A TID is distinct from a (MID). The MID identifies the merchant account, while the TID identifies one physical or virtual terminal underneath that account.
Key facts
- Unique to each individual terminal, never shared between devices
- Typically an eight-digit alphanumeric code assigned by the payment processor
- Distinct from the MID, which identifies the merchant account rather than the device
- Appears on transaction receipts and processing records
- Used for transaction tracking, dispute resolution, and fraud monitoring
How it works
When a payment is taken, the terminal stamps its TID onto the transaction record. That record travels with the payment through the processor and the , so the resulting can be tied back to a single device.
Each TID links a transaction to specific terminal hardware, its software configuration, and its physical location. Every payment device gets its own TID, from fixed checkout terminals to mobile readers, contactless devices, and pay-at-table systems.
TID vs MID
| Attribute | Terminal ID (TID) | Merchant ID (MID) |
| Identifies | A single terminal or device | The merchant account |
| Scope | One per device | One per merchant account (can cover many terminals) |
| Main use | Pinpointing which device processed a payment | Routing and settling payments to the merchant |
Why it matters
Because a TID points to one device, it lets merchants locate a specific transaction fast when a refund or dispute comes in, rather than searching an entire account's activity. Processors use the same per-terminal view to monitor transaction volumes and flag unusual patterns at the device level, so a compromised or malfunctioning terminal can be isolated instead of the whole account.
