1. "With whom does he usually have lunch?" Formal and 100% correct book English. 2. "Whom does he usually have lunch with?" Formal and correct book English. But most Americans do not use "whom" in most sentences. For example, even newspapers have sentences such as " WHO will that company choose as its new leader?" (Instead of the grammatically correct: "WHOM will that company choose as its new leader?" In other words: "That company will chose WHOM as its new leader?")

- With whom does he usually have lunch? You might hear a police officer or a 'Lady' in a period drama ask a question in this form, for example. And one can imagine every vowel annunciated with precision. - Who does he usually have lunch with? is the everyday version with approximately 4 schwa sounds in normal native British English.

Both versions are very correct, and good job remembering to full a preposition with "whom" rather than "who," a mistake so many native speakers make that it will probably eventually become the standard. There is a difference though, but not with meaning. It's a question of tone/register. The sentence you wrote is highly formal and as such has a sort of impersonal quality. The second is semi-formal and has a normal, everyday quality. So keep in mind your audience and the context when deciding which to use!

Hey Anoush, So both are grammatically correct, yet as already started above, the first question is VERY formal. It would be odd to hear this in a relaxed conversation with friends. To me, it's very 'posh British' 😊 All the best!

Hello, both structures are correct. The first structure is used more in a formal setting than the second one, which is more casual. There are also many ways to construct this question, such as: "Usually, he's having lunch with whom?" "With whom is he usually having lunch with?"