Does “Thanks a Lot” sound too casual for showing gratitude to someone in a higher position

Question

I'm thinking probably... because of "a lot"

Answer 1

Not only does it sound informal, but both Thanks! and Thanks a lot! are frequently used ironically - frequently enough that they should be avoided anytime there's even a slight chance of ambiguity. I would never use "thanks a lot" to my boss or supervisor unless we also happened to be friends.

It would be hard to go wrong with Thank you, Thank you very much, or Many thanks.

Answer 2

Yeah, it will probably sound a bit too casual, if you are addressing someone in a higher position.
Not unless the person who is in a higher position doesn't mind, or you and that person are in close standing. Otherwise, I would say:

Thank you very much!

Answer 3

Depends what you mean by "higher": if it's somebody you'd still be on fairly informal terms with (e.g. first name terms, or non-honorific terms if your native language has such a thing), then "thanks a lot" is fine. If the context demands use of more formal language, or if you're in doubt, then you can't go too wrong with "thank you very much".