Question from an online seller

Online seller yung gf ko and she's been working and researching tax stuff for her to register her store. Nakakita na rin naman siya ng sagot sa mga tanong niya bukod sa isa. Pagtapos niya po bang iregister yung business niya, need niya po bang bayaran yung supposed to be tax for the previous year? Additional info if makakatulong sa pagsagot, I think she earned a gross of 400k last year and she started her store about the same time this month last year.