Lewis symbol of sulphite ion is given as 

Formal charge on sulphur atom is 

Formal charge on S - atom:

$$\begin{gathered} \mathrm{Formal} \mathrm{charge}=\mathrm{Valence} \mathrm{electrons}- \\ \left[\mathrm{non} \mathrm{bonding} \mathrm{electrons}+\frac{\mathrm{bonding} \mathrm{electrons}}{2}\right] \\ \mathrm{Formal} \mathrm{charge}=6-\left[0+\frac{12}{2}\right]=6-6=0 \end{gathered}$$