A customer ID is the ten-digit number Google gives every Google Ads account, written in the format 123-456-7890. It identifies the account when you link it to other tools, invite someone to manage it or speak to Google support. You will often see it shortened to CID.
How the customer ID works
The number appears at the top of the Google Ads interface, next to the account name, and in the account switcher if you have access to more than one account. It stays the same for the life of the account.
Each manager account has its own customer ID too. That causes most of the confusion: an agency or consultant managing your ads will have a manager account ID that is different from your advertising account’s ID. When someone asks for “your customer ID”, they almost always mean the account where your campaigns and spend sit.
The customer ID is also separate from your billing identifiers. Your payments profile and billing account have their own numbers, which appear on invoices alongside it. When a form or a support agent asks for an ID, check which one they mean before you send it.
Knowing an account’s customer ID gives nobody any access. It is an address, not a key. To manage the account, a person needs to be invited by email under the access and security settings, or the account needs to accept a link request from their manager account.
Why it matters
You need the customer ID whenever you connect Google Ads to something else: linking Google Ads with GA4, connecting Merchant Center for Shopping, joining a manager account, setting up offline conversion imports, or giving a third-party reporting tool read access. Support will ask for it before discussing any problem.
It also matters for ownership. When a UK business parts company with an agency, the first question is whose account the campaigns live in. If the agency created the account under its own manager account and its own billing, the history, conversion data and audience lists may effectively belong to them. Knowing your own customer ID, and confirming you have admin access to it, protects years of data.
Common mistakes
- Sending a manager account ID when an advertising account ID was needed, or the other way round.
- Sharing a Google login password with a freelancer instead of inviting them with the right access level.
- Letting an agency create the account in its own name, so the business has no admin user of its own.
- Opening a second account by accident during sign-up and running campaigns in one while billing sits on the other.
- Treating the customer ID as confidential when it is safe to share, while being careless with the login itself.
How to act on it
Log in, note the ten-digit number at the top of the screen, and keep it with your other business account details. Then open Admin, Access and security, and check that at least one person inside your business holds admin access. If only an agency or a former employee has admin rights, fix that first.
When you hire help, send your customer ID and ask them to request access from their manager account, or invite their email address directly. You keep control, and you can remove their access in a minute if the arrangement ends. Checking account ownership and access is one of the first things I do when taking on Google Ads management.