I could well be wrong and I don't want to go into specifics here, but...
Let's assume I know of a business that in reality generates a few hundred thousand euros in revenue and yet shows a P+L with revenue far in excess of those numbers. This could imply they are laundering money — paying some tax just to get the money into circulation.
Who would I report this suspicion to?
If I were proven right, would there be a reward?