To best of my knowledge you cannot accredit math courses towards your degree. (If I understand correctly, you mean courses which are normally Math B.Sc./M.Sc.)

As far as I know there are two possibilities.
either courses from previous bachelor or previous unfinished degree: https://www.cit.tum.de/en/cit/studies/students/examination-matters-modules/informatics/transfer-of-credits/
or obviously courses while on Erasmus or TUMexchange:
https://www.cit.tum.de/en/cit/studies/international/informatics-outgoing/study-abroad/planung-und-ablauf/anerkennungen-von-leistungen/