Also called: Service Establishment Number, Amex SE Number
What an SE Number is
An SE Number, short for Service Establishment Number, identifies a merchant or establishment in American Express systems. American Express assigns Merchant Numbers after approving an application to accept its cards. You use the number to identify your business when communicating with American Express, and you are responsible for safeguarding it.
The term is Amex-specific in this context. In American Express Cardrefresher data, the 10-digit American Express Merchant ID corresponds to the Service Establishment Number. That does not establish one universal format for every system that handles SE Numbers.
An SE Number identifies your Amex establishment; it does not set your processing rate.
How American Express uses the number
Your Merchant Number connects Amex activity to the establishment that accepts the card. The American Express merchant guide requires separate Merchant Numbers for card-present and card-not-present charges. If you accept Amex in person and online, that separation means your business can have more than one Amex number.
Keeping the right number with the right sales channel supports accurate transaction records and reconciliation. If an online transaction is associated with the wrong establishment number, your records can become harder to match to the related Amex activity. Keep your business and acceptance-channel details current when they change.
How an SE Number differs from a Merchant ID
A Merchant ID (MID) is the general identifier used for a merchant account or processing relationship. An SE Number is the American Express-specific identifier for a merchant or establishment. In some Amex systems, the Amex Merchant ID and SE Number refer to the same number, so the labels are not always separate identifiers.
Do not assume that your processor's MID is interchangeable with your Amex SE Number. If your business has multiple locations or accepts Amex through separate in-person and online channels, match each identifier to the account and channel it represents before reconciling transactions.
What you can actually change
An SE Number is an identifier, not a negotiable rate or a processing-fee category. Focus on accurate account records and matching each Amex number to the correct establishment and sales channel.
- Record the Amex SE Number alongside the establishment and acceptance channel it identifies.
- Keep separate in-person and online Merchant Numbers distinct in your payment and accounting records.
- Check that Amex transaction records reconcile to the correct business location and channel.
- Protect the number and update business details when your locations or methods of accepting Amex change.
- Match each number. List your Amex SE Numbers by location and acceptance channel so staff can match transactions to the right records.
- Separate sales channels. Keep in-person and online Amex activity associated with their respective Merchant Numbers.
- Reconcile Amex activity. Compare your Amex transaction records with your business and location records to spot mismatches.
Frequently asked questions
What does SE stand for in payment processing?
For American Express, SE stands for Service Establishment. The SE Number identifies a merchant or establishment in Amex systems, and in some Amex records it corresponds to the American Express Merchant ID.
Is an SE Number the same as a Merchant ID?
They can refer to the same number in American Express systems, but the terms have different scope. SE Number is Amex-specific, while Merchant ID is a general term for an identifier used in a merchant account or processing relationship.
Does an SE Number affect my processing fees?
The SE Number identifies your Amex establishment. It does not itself set a processing rate or add a card fee, so review your actual pricing and fee lines separately from your account identifiers.