Apple’s App Store business model is facing another major legal challenge, with the US Supreme Court clearing the way for a lower-court process that could determine how much Apple is allowed to charge developers on purchases made outside its App Store payment system.

The dispute stems from the long-running Apple v Epic Games battle. A US judge ordered Apple to allow developers to direct customers to alternative payment options, after finding Apple had not complied with an earlier injunction.

Apple had sought to pause the latest proceedings while it pursues its appeal before the Supreme Court. The court initially granted a brief administrative stay, but subsequently rejected Apple’s bid for a longer pause, allowing the commission-rate proceedings to continue.

The battle centres around the question of how much Apple can charge when it is not processing the payment itself. Apple has proposed a commission of up to 15% for standard apps, 10% for some specialised programs and subscription renewals, and 5% for developers eligible for its Small Business Program.

Apple’s standard App Store commission has historically been 30%, with a reduced 15% rate applying to some developers and transactions.

Epic Games is challenging Apple’s proposed fees, arguing they go beyond what the court allows for purchases made through alternative payment systems. The eventual ruling could affect the overall economics of app stores.

For consumers, the App Store commissions are a cost that developers will either have to absorb or pass on. And a lower fee could give developers more room to cut prices, invest in their products or improve their own margins.

Meanwhile, Apple is fighting hard as the App Store is a crucial part of the company’s services business. Changing the commission model could have implications for its revenue and for the way it controls transactions across the iPhone ecosystem. Apple argues its fees reflect the value of its distribution platform, technology and services.