It depends on the context. Here are some examples from my experience: Congratulations for/on + (-ing) e.g. "Congratulations for/on finishing your degree" Congratulations to + (person) e.g. "Congratulations to you for finishing your degree" Congratulations on + (noun) e.g. "Congratulations on your degree" Hope that helps!

Congratulations on the birth of your baby/ graduating with honors. Congratulations for being selected for the program. Please convey my congratulations to your dad for completing the marathon.