A reasonable Lewis structure is $$ H-O-\overset { + }{ N } (=O)O^- $$ .
ne of the oxygen atoms has a formal negative charge, and the nitrogen atom is quaternized and bears a formal positive charge. Of course, the molecule is neutral, and the Lewis structure reflects this.
Note that when nitric acid dissociates:
$$ HNO_3(aq)+H_2O(l) \rightarrow H_3O^+ + NO^-_3 $$
There are $$ 3$$ formal charges on the nitrate ion: $$ ^-O-\overset { + }{ N } (=O)-O^-$$.
The overall charge on the ion is still $$ -1 $$, but there is again formal charge separation in our representation of the anion.