What is the formula of potassium ammonium sulfate? I tried to get the formula of potassium ammonium sulfate. What I got is $\ce{K(NH4)2SO4}$ but I don't think this the right formula. I searched on the internet and found an answer ($\ce{KNH4SO4}$), but I don't think it is correct.

So what is the correct formula of potassium ammonium sulfate?
$\ce{K(NH_4)SO_4}$ is the correct formula. You have two unipositive cations and a single dinegative anion. The total charge must be zero.