What is the most polite way?

Please excuse my ignorance, I’m wanting to learn though.

I work in a bank and we often have people come in who speak different languages. They will often bring someone with them to translate. During these interactions is it more polite to speak to the interpreter? Or directly to the person who doesn’t understand me?

For example when asking for identification is it better to say, “do you have ID?” Or to say to the interpreter, “do they have ID?” I’ve never been on the other side of that and would just like to improve how I communicate with people. Does it make a difference or matter?