A hot potato: Apple is receiving plenty of flak from developers over the 30 percent cut it takes from in-app purchases, something that led to the current legal battle with Epic Games. Now, the situation has prompted Google to clamp down on those who circumvent its own store tax.

Google says that it has always required developers who distribute their apps on the Play Store to use its billing system if they offer in-app purchases and pay a 30 percent fee from the payments. But some developers, including Netflix and Spotify, prompt customers to pay directly using a credit card, thereby avoiding Google's tax.

Google says less than 3 percent of the apps on its store offered in-app purchases over the last 12 months, and 97 percent of them use Google Play billing. The tech giant is giving new apps until January 20, 2021 to implement its billing system, while existing apps have until September 30, 2021 to comply.

Unlike Apple, Google has been lax with its in-app payment rules, but that started to change when Epic added a direct payment system to Fortnite Mobile, resulting in the battle royale title being booted from the Play Store.

Google cites Fortnite as being an example of Android's openness---the game can still be downloaded from Epic's store or other app stores, such as Samsung's Galaxy App store. Next year's Android 12 release will make it easier for people to use other app stores without compromising their device security.

"We only collect a service fee if the developer charges users to download their app or they sell in-app digital items, and we think that is fair," wrote Sameer Samat, Vice President of Product Management at Google. "Not only does this approach allow us to continuously reinvest in the platform, but this business model also aligns our success directly with the success of developers."

Last week saw the formation of The Coalition for App Fairness, a group of developers that include Spotify and Epic who are fighting for the removal of app stores' 30 percent fees. Its page is mostly aimed at Apple, but Google's clampdown will doubtlessly put it under the spotlight.