Applies to Dynamics 365 (online), version 9.x
Applies to Dynamics 365 (online), version 8.x

To maintain the integrity of your data, it’s a good idea to set up duplicate detection rules to reduce duplicate records in the system. Remember that after you create duplicate detection rules, you need to turn them on.

  1. Make sure that you have the System Administrator, System Customizer, Sales Manager, Vice President of Sales, Vice President of Marketing, or CEO-Business Manager security role or equivalent permissions.

    Check your security role

    1. Follow the steps in View your user profile.

    2. Don’t have the correct permissions? Contact your system administrator.

  2. Go to Settings > Data Management.

  3. Choose Duplicate Detection Settings.

  4. Select or clear the Enable duplicate detection check box.


    If your system contains a large number of records, checking for duplicates can impact performance.

  5. If you’re turning duplicate detection on, select or clear the check boxes to set when duplicates are detected:

    • When a record is created or updated

      The system checks for duplicates when a user enters or updates records.


      Duplicates aren’t detected when a user merges two records, activates or deactivates a record, or saves a completed activity.

    • When Dynamics 365 for Outlook goes from offline to online

      For users of Dynamics 365 for Outlook, the system detects duplicates when the user synchronizes their data after working offline, as long as users have enabled duplicate detection in Outlook. To enable duplicate detection in Outlook, choose File > Dynamics 365 > Options. Choose the Local Data tab, and then select the Enable duplicate detection during offline to online synchronization check box.

    • During data import

      When you use the Import Data wizard to bring in contacts, leads, accounts, or other types of data, the wizard detects any duplicate records as long as you enable duplicate detection in the wizard. More information: Import accounts, leads, or other data

  6. Choose OK.