American Express Payment Designation In order for Live eftpos to process American Express transactions and settle American Express payments alongside Visa and Mastercard, we require the following information to be completed.Step 1Please provide your American Express Service Establishment (SE) number (Your American Express Service Establishment number can be found in your American Express Online Portal, or on your American Express statement) Step 2Download the American Express Payment Designation form, complete and upload below. Step 3Please upload your completed American Express Payment Designation formMax. file size: 10 MB.