Is it required etiquette to wear a white t-shirt under a dress shirt and tie?

I made it a requirement that my officers wore a white t-shirt under their dress shirts. it's better because dress shirts can be see-through. It also keeps the sweat from the armpits from discoloring the dress shirt. Plus, if they are tan, or have a lot of chest hair, it will show through the shirt and look terrible. Usually a short-sleeve one is good :)

I actualy wear a dress shirt and tie to work. And I always wear a white shirt under my dress shirt. And it has sleeves. It helps if I happen to sweat any that my dress shirt stays dry and looks professional all day.

Whatever makes a person comfortable they should wear. I would think you would wear a tee shirt under your dress shirt if the shirt is very thin but if it is a regular shirt you can do without wearing a tee shirt. Tee shirt under a regular shirt is more suited for the winter.

It's not REQUIRED, it's just personal preference. I wouldn't do it because I'm already hot natured, so adding a second layer, like an under shirt, would just make things worse.

Yup! They have to be tank tops (as we girls call it)