A cobalt(III) centre form a complex with five ammine ligands, and ONE sulfate counter ion. What is its likely formulation?

Given the formula, the sulfate probably occupies the $1$ coordination site on the octahedral cobalt centre.
Given this formulation, the parent complex ion is likely, ${\left[C o {\left(N {H}_{3}\right)}_{5} \left(O S {O}_{3}\right)\right]}^{+}$, in which the sulfato ligand acts as a unidentate donor towards the octahedral $C o \left(I I I\right)$ centre. I don't know the lingo with respect to secondary and primary valences.