iOS and OSX add +1 day to contacts birthday and anniversary when syncing from/to Outlook.com

12/21/18 - An Outlook.com engineer has confirmed that they are currently waiting for deployment of the fix for all affected users. 

12/22/18 - An Outlook.com engineer has confirmed that they are coordinating a fix with Apple. Expected Date: Unknown

03/27/18 - Apple has released iOS 12.2 that fixes the sync issue with iOS devices for Outlook.com Contacts. (FIX: Unsync / Re-sync contacts)

What's fixed:

• iOS Contacts (Synced from Outlook.com)

What's still broken:

• iOS Contacts (Synced from Exchange) per some users above
• OSX Contacts (Synced from Exchange and Outlook.com)

Additional Notes:

Some users above state that 12.2 has not fixed their Outlook.com contact and that some contacts still have the incorrect date. 

This might be due to the fact that a contact which was displaying the incorrect date on iOS for example, was edited and saved from an iOS device that altered the date on Outlook.com to the incorrect date. 

I had a contact who's birthday is 10/23, but recently forgot I updated his home address, so when it saved back to Outlook.com, it saved the new address and the incorrect 10/24 birthday. 

Validation Steps Taken:

• Unsync Outlook.com contacts / Resync Outlook.com contacts ✔
• Create a contact in Outlook.com > It crosses over to iOS 12.2 with no issues (DOB & Anniversary date) ✔
• Modify birthday in Outlook.com > It crosses over to iOS 12.2 with no issues (DOB & Anniversary dates) ✔
• Create a contact in iOS 12.2 > It crosses over to Outlook.com with no issues (DOB & Anniversary dates) ✔
• Modify birthday in iOS 12.2 > It crosses over to Outlook.com with no issues (DOB & Anniversary dates) ✔

---------------------------------- HISTORICAL INFORMATION (ORIGINAL TICKET) --------------------------------------------------

After experiencing this issue a second time, I was able to stumble upon this thread which is now locked*

Locked Thread: birthday dates move forward one day when entered in outlook.com but synced to mobile (British summer time)

Created a copy of this thread at Apple as well: iPhone (iOS) and Outlook.com synchronization moves contact birthday date forward +1 day

Devices and Applications Affected:

• Contacts in iOS
• Contacts in OSX

Confirmed Contact Fields Affected:

• Date of Birth
• Anniversary*

*steps below use DOB as an example, but the same behavior happens to Anniversary date field.

Below are the steps and actions that make this problem easy to reproduce:

• Create a completely new account @outlook
• Add contacts with birthdays
• Link this account to an iPhone
• Contacts on the iPhone will all display birthday +1 day after synchronizing

Contacts created on Outlook.com

• When the contacts sync to the iPhone the date automatically changes to +1 on the phone for all contacts
• If a change is made to a contact (any contact fields) on the iPhone, the +1 day DOB will sync back to Outlook.com when those changes are pushed.
• Going to Outlook.com to verify this info shows the following:
  • Contact View Mode: shows correct birthday
  • Contact Edit Mode: shows dob +1 day

Contacts created on iPhone (iOS 12.1.0)

• When a contact is created on the iPhone, the date will be accurate and syncs correctly back to Outlook.com
• If a change is made on Outlook.com, when the phone syncs to Outlook.com it will update the DOB on the phone by +1
• If a change is made again on the iPhone (any contact field), when the phone syncs changes back to Outlook.com, it will update the new DOB to +1.
• Going to Outlook.com to verify this info shows the following:
  • Contact View Mode: shows correct birthday
  • Contact Edit Mode: shows dob +1 day

It seems like the break is on how Outlook.com and iPhone synchronize this information. It's also strange the Outlook.com Contact View Mode shows one date, while Contact Edit Mode shows a different date than the displayed one.

These steps are easy to reproduce on my end on both my account and the new account created. 

Some people state that since iOS12 that synchronization of Anniversaries are also affected. I did not try to validate those steps in this testing.

Edit 12/14 - Adding Additional Troubleshooting Info

Contacts created on Outlook.com and linking account to OSX and iOS:

STEPS TAKEN / Observation

1. Create a new contact with a birthday in an outlook.com account
2. Add account to iOS or OSX and that sync includes contacts to be part of the sync
3. When looking at the contact in iOS or oSX, the contact’s birthday will be one day after the entered birthday on step 1
4. Correcting the birthday in iOS or OSX will correct the birthday in Outlook.com when syncing
5. Make a change to the contact’s field in Outlook.com
6. When checking iOS or OSX, the changed field has updated and the birthday field will display a day after the date displayed in Outlook.com when the contact was saved

**Issue 1:**Every time iOS or OSX refreshes from the server, it will add +1 day to the date saved in Outlook.com 

**Issue 2:**If a contact with the +1 date on iOS or OSX is updated on those devices, they will also update the contact with the incorrect date on Outlook.com 

Contacts created on iOS and OSX and synced to Outlook.com

STEPS TAKEN / Observation

1. Create a new contact with a birthday in iOS / OSX for the Outlook.com account
2. When confirming birthday in Outlook.com, the contact will have the correct birthday
3. Make a change to a contact field in Outlook.com
4. When checking iOS or OSX, the changed field has updated and the birthday field will display a day after the date displayed in Outlook.com when the contact was saved

**Issue 1:**Every time iOS or OSX refreshes from the server, it will add +1 day to the date saved in Outlook.com Issue 2: If a contact with the +1 date on iOS or OSX is updated on those devices, they will also update the contact with the incorrect date on Outlook.com 

Contacts created an Exchange 2010 and linking account to OSX and iOS:

STEPS TAKEN / Observation

1. Create a new contact with a birthday in Exchange account
2. Add Exchange account to iOS or OSX and that sync includes contacts to be part of the sync
3. When confirming birthday in iOS or OSX, the contact will have the correct birthday
4. Make a changes to the contact in iOS or OSX
5. When checking Exchange, the changed field will have updated and the date of birthday remains correct

No Issues with this scenario

Contacts created on iOS and OSX and synced to Exchange 2010

STEPS TAKEN / Observation

1. Create a new contact with a birthday on an iOS / OSX for the Exchange account
2. When confirming birthday on Exchange account, the contact will have the correct birthday
3. Make a change to a contact field on Exchange
4. When the contact on iOS or OSX update, the birthday remains correct

No Issues with this scenario

Contacts created on GMAIL and linking account to OSX and iOS:

STEPS TAKEN / Observation

1. Create a new contact with a birthday on the Gmail account
2. Add Gmail account to iOS or OSX and that sync includes contacts to be part of the sync
3. When confirming birthday on iOS or OSX, the contact will have the correct birthday
4. Making changes on iOS or OSX do no alter the birthday abnormally

No Issues with this scenario

Contacts created on iOS and OSX and synced to Gmail Account

STEPS TAKEN / Observation

1. Create a new contact with a birthday on an iOS / OSX for the Gmail account
2. When confirming birthday, the contact will have the correct birthday on the Gmail Account
3. Make a change to a contact field on Gmail
4. When the contact on iOS or OSX update, the birthday remains correct

No Issues with this scenario