 Now, a new plan to tax the world's billionaires will be the top item in a forthcoming meeting of the leading G20 developed and developing nations next month. The meeting will be held in the Brazilian city of Rio de Janeiro, and the plan was commissioned by Brazil's government, which currently holds the chair of the G20. The plan, released this week, envisages a new level of minimum tax on the world's richest 3,000 people.