In the compound SO3 sulfur trioxide , the oxidation state of sulfur is +6. Here's how to determine it:1. Oxygen typically has an oxidation state of -2.2. There are three oxygen atoms in SO3, so their combined oxidation state is 3 x -2 = -6.3. The overall charge of the compound SO3 is neutral 0 .4. To balance the oxidation states and achieve a neutral charge, the oxidation state of sulfur must be +6.