Try this: https://office365itpros.com/2023/09/25/dynamic-administrative-units-ps/

Well, I was wrong in my advice. The right way to do this is to:

1. Create a new admin unit.
2. Update the new admin unit with the properties to make it a dynamic AU.

I’ve worked out the basics of a script and will publish it when it works the way I want it to.

Given a CSV file like this:

Name
Information Technology
Artificial Intelligence
Generative AI

You could do something like this:

ForEach ($AU in $AUs) {
$Description = (“Dynamic administrative unit created for the {0} department created {1}” -f $AU.Name, (Get-Date))
$DisplayName = (“Dynamic administrative unit created for the {0} department” -f $AU.Name)
$MembershipRule = “@{membershipRule=’user.department eq ” + “‘” + $AU.Name + “‘” + ‘”‘ + “‘}”
New-MgBetaAdministrativeUnit -Description $Description -AdditionalProperties $MembershipRule -Description $Description -MembershipType ‘Dynamic’ -MembershipRuleProcessingState ‘On’
}

I can’t test this because my Azure AD Premium licenses have expired and I am awaiting renewal, but the code above creates the rule in the correct format.

Isn’t PowerShell wonderful?

For now I’m going to keep supporting this script but I am happy AADAU has gone GA. I think it was preview since 2014 which was the longest preview product I have ever seen.

https://github.com/JBines/Set-AADAUDynamic

I wouldn’t use custom security attributes. There are fifteen custom extension attributes that are designed for this purpose. I compare them against Azure AD custom security attributes in https://practical365.com/azure-ad-custom-security-attributes-exo/

Here’s an example of using custom attributes in a dynamic distribution list. The same concept extends to dynamic Azure AD groups: https://office365itpros.com/2021/01/18/dynamic-distribution-lists-filters/

Does “custom security attributes” solve this for me or can they be used in the syntax rule for a dynamic assigned group? Thanks for one of the best blogs and materials for microsoft365 out there!

Given that MemberOf is still a preview feature that offers limited functionality, its lack of support in dynamic administrative units is unsurprising.

I have tried to tested but it is not even able to create the dynamic role.

did it work with you ,as I need to add users to an AU based on their group membership.