Calendar isn't sharing properly

I created this User Tip to serve as the basic framework for managing and recovering Calendar - Calendar - syncing with iCloud - Apple Community

Calendar can sometimes become scattered or multiplied when syncing or when changing devices. To ensure that Calendar is always correct, follow these few simple steps. These steps include a Mac but do not include the steps for a PC. These steps include the use of iCloud and do not require purchasing additional storage.

If you are missing Calendar events because you recently deleted an email account, add it back until you perform these steps.

If you do not wish to use iCloud choose one email account to use as the default to prevent Calendars from being lost, scattered, or mismanaged.

Step one

(Skip to step two if you do not own an iPhone/iPad)

On iPhone/iPad

1. Go to settings>mail>accounts>tap any account and turn on Calendar (repeat for all accounts).
2. Go to settings>Apple ID (your name at the top>iCloud>iCloud backup - turn on and select "back up now."
3. Go back to settings>Apple ID>iCloud>turn Calendar off - choose to keep on device. Do not turn it back on yet!
4. Go to settings>mail>accounts>tap any account except iCloud - turn off Calendar (repeat for all accounts).
5. Go to settings>mail>accounts>tap iCloud - turn on Calendar. Stop here on the iPhone until you perform the Mac steps.

Step two

(Skip to step three if you do not own a Mac)

On Mac

1. Go to system preferences>internet accounts>tap iCloud account - turn on Calendar
2. Go to system preferences>internet accounts> Is Calendar turned on for all accounts?
3. Go to system preferences>iCloud>Calendar - uncheck that, and then check it again and it may ask to merge. This should force it to merge all the Calendars you have for the Mac.
4. Go to system preferences>internet accounts>tap any account that is not iCloud - turn off Calendar (repeat for all accounts).
5. Stop there and go to iCloud.com

Step three

On iCloud.com

1. Sign in and select Calendar - make sure they are correct.

Step four

On iPhone

1. Go back to settings>Apple ID>iCloud>turn Calendar on and merge.
2. Go to settings>Apple ID>iCloud>iCloud backup - turn on

Useful Links

Delete spam calendars and events on iPhone - Apple Support

If your iCloud Contacts, Calendars, or Reminders won’t sync - Apple Support

If you have duplicate events on your iCloud Calendar - Apple Support

Use iCloud calendar subscriptions - Apple Support

If you accidentally deleted your calendars, bookmarks, or contacts from iCloud - Apple Support

Limits for iCloud Contacts, Calendars, Reminders, Bookmarks, and Maps - Apple Support