RIYADH, Saudi Arabia (AP) — Saudi Arabia has announced a new tax code for oil and gas producers amid plans to publicly list shares of state-oil giant Saudi Aramco.

The new code, rolled out by royal decree from King Salman, taxes Aramco at 50 percent on income retroactively starting Jan. 1.

The government is preparing to list less than 5 percent of Aramco by next year on the Saudi stock exchange and an international exchange, possibly in the U.S.

The decree, published Monday in the Saudi Press Agency, imposes a 50 percent tax on oil and gas producers that have invested more than $100 billion in capital in the kingdom.

That figure jumps to 85 percent tax on producers with invested capital that does not exceed $60 billion.