Should I use the formal vs. informal “you” with my boss and superiors at work?

That’s a very subjective question… Heck, even I get confused sometimes! If it was up to me, I’d get rid of a few useless rules we have in French, but you can’t mess with the French Academy (look it up, it’s a bunch of old conservatives who define the “official” way to speak and write in French)…

So yes, in French we have two ‘you’: a formal version (vous) and an informal version (tu). Using the formal ‘you’ is called vouvoyer and using the informal version is called tutoyer.

So I guess the rule is this: if you start a conversation with a stranger or in a formal setting (like work), use the formal ‘you’ and if at some point your interlocutor feels like switching to informal, they’ll ask you to tutoyer each other. You can also offer to go informal yourself, by asking On peut se tutoyer? Going from vous to tu out of the blue might fry your brain at the beginning, especially if you’re from an english-speaking country where this kind of formality doesn’t exist, but at least you’ll avoid feeling awkward all the time.

At work, the expected level of formality depends on the company’s culture and your position. If you’re working in banking or insurance, you should be fine calling your boss tu, but you’ll probably stick to vous with your boss’s boss. Nowadays in multinationals, it’s ok to call everyone tu, except maybe the CEO if he’s old and somewhat traditional.