When giving your agency access to Google Tag Manager (GTM), you’ll have the option to either grant access at the Account or Container level. At Account level, users are given rights to view or administer, while at the Container level, they’ll be able to read, edit, approve, or publish.

Step 1: Login to Google Tag Manager at https://tagmanager.google.com/.

Step 2: To select Account Administrative View

• Click into the account or container you would like to add an agency to.

• Select “Admin” in the upper left-hand corner – this will give you access to the GTM administrative view.

Step 3: Under the “Account” or “Container” tab, select “User Management.” This is where users can be added and removed. You’ll also be allowed to modify permissions in this section as you’ll be able to see the list of people who have access to your GTM account.

Step 4: Click on the blue plus sign button in the top right corner of your screen, then “Add users”, which will direct you to the GTM invitation.

Step 5:Enter the email address of the user or users you would like to add. The users will receive an invitation via email.

Step 6:Permission need to be selected from the list provided ensuring that the permissions granted allow your agency the ability to complete the tasks you need their support on.

For Account permissions you will need to check “Administrator” as “User will already be checked”.

For container access, select the box next to the highest level of permissions you would like to grant to your agency, then click “Done”.

Step 7: Lastly, click the blue “Invite” button. This will send account access to your added users, who will need to accept the invitation in order to start working in your GTM account.

Sources:

https://saltbox.solutions/google-tag-manager-agency-access/

https://support.google.com/tagmanager/answer/6107011?hl=en

https://www.optimizesmart.com/how-to-give-someone-access-to-google-tag-manager-account/