Sharing Your Microsoft Advertising Account Number
To share Bing Ads access (now called Microsoft Advertising), email us your account number.  It's in the upper right corner when you're logged in at Ads.Microsoft.com
Microsoft account numbers are 8 digits long, start with an F or X.
We'll enter your account number into our Microsoft Agency Account, and a Bing Ads access request email will be sent to the address associated with that account.  Once you approve the access request, we'll have 3rd-party access to work in your account.
This provides us provisional 3rd-party access, so you maintain ownership and control of the account, and we won't have visibility into the financial information or other accounts that use the same Microsoft ID.