Gas companies will be forced to set aside 20% of exports for domestic use under a reservation scheme designed to shore up supplies and bring down prices for households and businesses on the east coast. The federal government announced the design of the reservation scheme on Thursday as part of a wider overhaul of the mechanisms regulating the gas sector . Under the policy, which will start on 1 July 2027, the three big Queensland-based gas exporters would be forced to preserve an equivalent of 20% of export volumes for east coast market customers. The companies would need to prove to the federal resources minister that their domestic supply obligations have been met to secure a permit to sell to the overseas spot market. Sign up for the Breaking News Australia email The 20% mandate sits in the middle of the 15%-25% range that the government canvassed with industry after announcing its commitment to a gas reservation on 22 December. It will not apply to contracts signed before that date.…