1. You should never wear tan shoes with navy suits.
2. You should match tan shoes with tan belts.
3. You should not match tan shoes with a tan belt. Belt must me much darker.
4. You should not wear a belt at all if you wear tan shoes.
IMO tan (not light brown, but tan) shoes look bright so if matched with tan belt it looks much too risky. So, I assume you either should wear a black belt with tan shoes or no belt at all. The question is if these two options are allowed stylewise.