Formal:
* Salamat po. (This is the most common and polite way to say thank you.)
Informal:
* Salamat.
* Maraming salamat. (This means "Thank you very much.")
* Salamat ng marami. (This also means "Thank you very much.")
Other expressions:
* Pasasalamat. (This means "Thank you" and is a more formal way of saying it.)
* Nagpapasalamat ako. (This means "I am grateful" and is a more formal way of expressing thanks.)
The choice of which phrase to use depends on the context and your relationship with the person you are thanking.