What Apple says happens

Apple's guidance is to download or remove content that exceeds your new storage amount before you downgrade or cancel. If your content is over the limit, iCloud stops syncing and updating, and iCloud backups won't complete. The change takes effect after your current billing period ends. Apple: Downgrade or cancel your iCloud+ plan →

The order that keeps your photos

Each step makes the next one safe, so do them in sequence.

• 1Copy your library to your Mac. The quickest way is Transfer in Raza Photos, which copies your whole library from your iPhone over Wi-Fi. The full guide →
• 2Check that it arrived. Browse the library in Raza Photos and open a few older photos.
• 3Back it up. Once iCloud Photos is off, your Mac may hold the only full copy. A simple backup plan →
• 4Turn off iCloud Photos on every device, under Settings → [your name] → iCloud → Photos.
• 5Cancel or downgrade. On an iPhone with iOS 18.4 or later, open Settings → [your name] → Subscriptions → iCloud+ and tap Cancel Subscription, or See All Plans to downgrade. On a Mac with macOS 26, open System Settings → Apple Account → iCloud, click Manage Plan under iCloud+ Features, then Cancel Subscription or See All Plans. Older versions use slightly different menus, and Apple's page lists them.
• 6Wait for the period to end. Your plan runs until the end of the billing period. After that you're on the free 5 GB tier.

Things people forget

iCloud+ is more than storage. Apple notes some features may not be available after you downgrade or cancel, so check what you use besides photos.

iPhone backups to iCloud count against storage too. If storage runs out, those backups stop completing, so plan another backup for the phone itself, for example to your Mac.

Cancelling doesn't have to be final. Because your library is now on your own hardware, you can always choose a plan again later. Nothing about leaving locks you out.