A customer conducts an international wire and tells the bank the purpose of the wire. Do you request supporting documentation for that wire? (Ex: invoice, sale of a house, etc) If the customer doesn't provide it, you reject the wire?

that is a sliding scale for me...how well known is the customer, amount of wire, frequency of other wires, does this match a pattern, does customer seem up front or evasive, and a host of other things...

Same here

Thank you. I was curious as to the answers.

Anyone collect for EVERY wire over a certain threshold regardless if its an existing customer for years or brand new?

No

We ask the purpose of all domestic wires over $X amount and all foreign wires over $Y amount. If it's a large transaction or something unusual based on the customer's activity, we will ask for supporting documentation.