In short: yes, sure. However, in my opinion you’d only say that for example, in a context of comparison. This person may be different from others because he’s taking the SATs. You could say: “Oh that’s the SAT-taker. I wonder why he chose that over our curriculum?” Taking the SATs makes him stand out. In America, where SATs are the norm, to describe someone as a SAT-taker would be…strange, as almost everyone takes the SATs. ✌️☺️