Apple has begun sending last-minute reminders to users currently enjoying 20GB of free iCloud storage, warning that from September 30, it will downgrade their accounts unless they take action.

Introducing iCloud alongside the iPhone 4S and iOS 5 in October 2011, Apple offered paid MobileMe subscribers a free 20GB extra iCloud storage if they migrated their accounts over to its new online storage platform. This meant that users switching from MobileMe to iCloud received a total of 25GB storage space (including the free 5GB offered to new users).

Originally, Apple placed a June 30 expiration on the free storage it offered, but later extended that to September 30. With six days before the cut-off date, iCloud users that have more than 5GB synced to their iCloud accounts are now receiving these ‘downgrade’ emails.

The email warns that if they don’t free up space and come in under the 5GB free limit or pay for the extra storage, apps will no longer back-up documents to iCloud:

Screen Shot 2012 09 24 at 11.03.21 520x328 Apple warns ex MobileMe users with 20GB free iCloud storage of downgrade coming Sept. 30

The important part:

Your iCloud storage will be reduced to 5 GB on 09/30/2012.
However, you are currently using more than 5 GB.

Unless you take action before your downgrade takes effect, backups to iCloud will stop, and apps will no longer be able to save documents to iCloud. You can either free up storage or cancel your downgrade to keep your current storage plan for another year.

Notice that Apple isn’t stating documents and settings will be deleted if the user doesn’t take appropriate action, it simply states that “backups to iCloud will stop, and apps will no longer be able to save documents to iCloud.”

Data won’t be deleted, but any new iCloud syncs will be blocked and new data will not be saved. Rather than being an opt-out process (like a Netflix free trial) it’s opt-in and its likely in place to protect customers from unwanted charges.

Upgrades start at $20/£14 for 10GB and range up to $100/£70 for 50GB, with Apple charging users yearly. This does not include the 5GB free storage, so users will receive 15GB, 25GB and 55GB total storage depending on their upgrade.

Image Credit: Justin Sullivan/Getty Images