JAKARTA, May 21 (Reuters) - Indonesia will tighten rules on natural resource export earnings retention starting June 1, including requiring most exporters to park receipts with state banks, in a bid to increase domestic foreign exchange supply and help the falling rupiah.

 Much of the details in the new regulation matched a plan the government announced in late 2025. Here are details according to a presentation by authorities on Thursday: 

o Exporters of all natural resources, except for oil and gas, must keep their earnings in state-owned banks for at least 12 months. They previously were allowed to keep their funds in any Indonesian-based bank.

o Under the new regulation, only as much as 50% of the proceeds can be used for business operations if they are converted into rupiah.

o Previously, exporters were allowed to use all of their funds if converted into rupiah.

o Foreign currency proceeds can be placed in special instruments issued by the central bank, or foreign currency bonds offered by the government.

o Such papers can then be used by exporters as collateral to get rupiah loans.

o The central bank will expand the foreign currencies it offers for its instruments beyond the U.S. dollar, such as by adding Chinese yuan.

o Oil and gas exporters will still be required to keep only 30% of their proceeds for a minimum of three months.

o There will also be special rules for miners covered by bilateral rules or other deals with foreign governments.

(Reporting by Bernadette Christina; Writing by Gayatri Suroyo; Editing by Martin Petty)