California's New Law Will Force Windows, Mac, and Linux to Verify Your Age

California is coming for your operating system. Not in a dramatic way, but in the quiet, bureaucratic way that tends to actually stick.

Governor Gavin Newsom signed AB 1043, the Digital Age Assurance Act, into law in October 2025. It passed both chambers of the California State Legislature unanimously, which is worth noting. No pushback. None.

So what does it actually do?

Starting January 1, 2027, every operating system provider, think Microsoft, Apple, and yes, Linux distributions, will be required to build a real-time API directly into their OS. At account setup, users in California get asked for their age. That age then gets sorted into one of four brackets:

• Under 13
• 13 to 16
• 16 to under 18
• 18 or older

When you download or launch an app, developers who request that data will receive your age bracket. The stated purpose is content distribution, so platforms serving up age-restricted content know who they're serving it to.

This isn't just a mobile thing either. PC users on Windows, Mac, and Linux are all in scope if they're based in California.

The law doesn't technically kick in until 2027, but that's not far off. OS providers will need time to build and test compliant APIs, which means the clock is already ticking behind the scenes at places like Microsoft and Apple. Whether Linux distros, many of which are community-maintained projects, realistically pull this off is a different question entirely.

Privacy advocates will have plenty to say about this. Collecting age data at the OS level and piping it to third-party developers on app launch is a significant shift from how things currently work. The law targets California residents, but given that Windows and macOS are global products, the practical implementation will likely touch far more than just one state's worth of users.

Whether other states follow California's lead, as tends to happen with tech legislation, remains to be seen. For now, 2027 is the date to watch.