Had a beast of a time finding this one.
You might have noticed that photo tagging is not enabled by default when you post new photos to your Facebook Like or Fan Page. If you’re logged in as an admin of the page you can tag photos, but tagging is disabled for your Facebook fans.
There doesn’t seem to be a setting that is easily toggled. I found a solution in a Facebook discussion forum.
1. Find your Facebook Page ID (go to your Facebook page and click on Edit page. The id will be in the URL after &id=__________)
2. Go to this URL http://www.facebook.com/pages/edit/app_settings.php?id=xxxxx&aid=2305272732 where xxxxx is your Facebook Page ID
Toggle the setting “Allow all fans to tag photos” and Save.