Indonesia, the world’s biggest coal exporter, is considering imposing an export levy on the fossil fuel to boost state revenues, a senior government official said.

The tariff would be collected from miners only when coal prices are high, with authorities potentially including it in the 2026 budget plan, Energy and Mineral Resources Deputy Minister Yuliot Tanjung told reporters in Jakarta on Tuesday.

President Prabowo Subianto’s administration has been rolling out an array of revenue-boosting measures to fund big-ticket spending plans, which include free meals for school children, and public housing. The mining industry, which is critical to Indonesia’s economy, has faced particular pressure.

The sprawling archipelago is the world’s biggest thermal coal exporter, and firms there have been hit by higher royalties and an obligation to keep earnings in local banks for a year. An export levy would add to the pressure on the sector, which is already dealing with a recent plunge in prices.

Energy and Mineral Resources Minister Bahlil Lahadalia confirmed on Monday that regulators were moving forward with the levy, which started as a proposal from parliament. A similar charge on gold exports was being considered.

“If prices are good, then they should share some of those earnings with the state,” he was quoted as saying by multiple news outlets. “But if prices aren’t economic, then we shouldn’t burden businesses.”

The government needs to study the plan further, and consider the sustainability of business and national energy security, along with the potential revenue increase, said Gita Mahyarani, acting executive director of the Indonesian Coal Mining Association. The association is seeking further clarity on the proposed levy, she said.

Shares of some Indonesian coal miners fell on Tuesday as the Jakarta Composite Index rose. PT Indika Energy and PT Bukit Asam both closed down 0.8%.

The plan creates uncertainty for local miners, and could add to refinancing risks for high-yield companies with limited liquidity and diversification, Mary Ellen Olson, a Bloomberg Intelligence analyst, said in a note. Indika Energy, PT Medco Energi Internasional, PT Mineral Industri Indonesia and PT Freeport Indonesia are potentially most at risk, she said.

— With assistance from Eddie Spence