"Ako" is used as a SUBJECT / OBJECT "Ko" is used as POSSESSIVE PRONOUN Example: Ako ay matangkad. (I am tall.) Ako ay naglalakad. (I am walking.) Tinawag mo ako. (You called me.) Ito ang pagkain ko. (This is my food.) "Ko" an also be used as a contracted form of "Ako" (as OBJECT) Example: Tinawag mo ko. (You called me.)

Depending on how you wanna construct your sentence. Ex. Adjective Ang taba ko. and Mataba ako. Both mean I am fat. Ex. Verb Nakain ako.

Ako is always used for adjectives.