Upon addition of Cs2AgBiCl6, the catalytic activity is enhanced which we may attribute to the superior absorbance of the Cs2AgBiCl6 perovskite. At highest perovskite concentration, surface defects of the Cs2AgBiCl6 likely compete with the electron transfer to g-C3N4, limiting NH3 production. This observation highlights the delicate balance required for optimal performance in the heterostructure system, requiring a fine tuning of the heterostructure composition.