I have written before that firing an agency rarely fixes the underlying problem, and that the system usually needs fixing first. This piece is the practical companion: when you have decided to switch, how do you do it without losing your ad account history, your conversion data or your tracking? The answer depends almost entirely on one question that is easy to ignore while things are going well: who actually owns each account? Run this checklist before you give notice, not after.
Step one: an ownership audit before you give notice
Notice changes the relationship. An agency that is leaving has less reason to help you untangle access, and some will slow down, even without bad intent. So the audit comes first, while everyone is still cooperative. Make a simple sheet with one row per asset: Meta business portfolio, each Meta ad account, Facebook Pages and Instagram accounts, Meta datasets and pixels, product catalogs, Google Ads accounts, any Google Ads manager account they are linked to, GA4 accounts and properties, Google Tag Manager accounts and containers, Google Search Console, Google Merchant Center if you sell online, LinkedIn Campaign Manager, the CRM, the email platform, the website hosting and domain registrar. For each row record three things: which business or person owns it, which people at your company have the top-level role, and which agency people have access and at what level. The rule I want to see on every row is that the company owns the asset and at least two named people at the company hold the highest role, so a single departure or locked login cannot lock you out. Anything that fails that rule is your pre-notice work list. Fixing it while the agency is still engaged is far easier than after.
Meta: business portfolio, ad accounts, Pages and pixels
On Meta, ownership sits with a business portfolio, formerly called Business Manager. The setup you want is your own portfolio owning your ad accounts, Pages, Instagram accounts and datasets, with the agency given access as a partner. Meta lets the owning business share assets with a partner's business portfolio using the partner's portfolio ID, at either full control or partial access, and Meta's help documentation notes that even a partner with full control cannot share the asset onward with another business; only the owning organisation can. That is exactly the control you want when changing agencies. The hard case is an ad account the agency created inside its own portfolio. Meta's help centre states that an ad account created in a business portfolio cannot be transferred to another business's portfolio. If that is your situation, you cannot take that account with you. You will need to create a new ad account in your own portfolio and rebuild campaigns there, so export everything first: campaign structures, audience definitions, creative, and historical performance reports. Pages and Instagram accounts are separate assets; check who owns those too, and request them into your portfolio if the agency holds them.
Google Ads: manager accounts and administrative ownership
Agencies usually manage Google Ads through a manager account, often called an MCC. Linking your account to their manager account is normal and does not by itself hand over ownership; Google's documentation is explicit that linking does not automatically grant administrative ownership. But a manager account can hold administrative ownership of a client account, and when it does, its administrators can do things like add or remove administrative users and transfer that ownership. So check two things. First, does at least one person at your company have Admin access directly on your Google Ads account, not just through the agency? Second, does the agency's manager account hold administrative ownership? If it does, ask them to remove or transfer it before the switch. To end the relationship, you can remove the manager's access from your own account in the Admin area under access and security, or the agency can unlink from their side. Google says your account keeps its own campaign history after unlinking. The caveat: if the agency used shared remarketing lists or a cross-account conversion tag from their manager account, those can stop working on unlink. Check conversion actions and audience lists before you unlink, and recreate any that live at manager level.
GA4, Google Tag Manager and the CRM
GA4: you want a company person with the Administrator role, which per Google's documentation is the only role that can manage users. Editor gives full control of settings but cannot add or remove users, so an Editor alone cannot remove the old agency. Roles set at account level carry down to every property, so check both levels when removing access. Google Tag Manager: access has two layers. Account-level permission is either Admin or User, and Admin is what lets someone create containers and change permissions. Container-level permission is Read, Edit, Approve or Publish, with Publish the only level that can push changes live. Your company needs an account Admin, and should hold Publish on every container. Before the switch, ask the agency to document every tag, trigger and variable and why it exists, and export the container as a backup. CRM: confirm the subscription is on a company contract and billing method, that a company person is the super admin, and that integrations feeding it, such as lead forms, ad platform syncs and offline conversion uploads, are running under company-owned connections rather than an agency user's login. Integrations tied to a departing person's credentials are the most common thing that silently breaks after a switch.
The handover checklist, in order
1. Complete the ownership audit and fix ownership gaps while the outgoing agency is engaged. 2. Make sure at least two company people hold top-level roles on every asset. 3. Export: campaign structures, audience definitions, creative files and copy, naming conventions, historical reports by month for at least the last year, and the GTM container. 4. Request written documentation of conversion events, tracking setup, offline conversion uploads, CRM integrations and any scripts or automated rules. 5. Give the new agency partner or user access under your ownership, at the lowest level that lets them do the job. 6. Run both agencies in parallel for a short overlap if the contract allows, so the new team can see live performance before taking over. 7. Check conversion tracking still fires correctly after the new team makes changes. 8. Only then remove the old agency: partner access on Meta, manager link on Google Ads, users in GA4 and GTM, CRM seats and integrations. 9. Rotate any shared passwords or API keys the agency used. 10. Record the final state of the ownership sheet and review it every quarter.
Sources
Meta Business Help Center, Give a partner access to business assets in your business portfolio: https://www.facebook.com/business/help/1717412048538897 Meta Business Help Center, About Account Sharing Limitation: https://www.facebook.com/business/help/563249781254715 Google Ads Help, About user access levels for your manager account: https://support.google.com/google-ads/answer/9977851 Google Ads Help, Unlink accounts from your manager account: https://support.google.com/google-ads/answer/7456531 Google Ads Help, About unlinking accounts from your manager account: https://support.google.com/google-ads/answer/7458428 Google Analytics Help, Access and data-restriction management: https://support.google.com/analytics/answer/9305587 Tag Manager Help, User permissions: https://support.google.com/tagmanager/answer/6107011
FAQ
Not if the agency created it in their business portfolio. Meta says an ad account created in a business portfolio cannot be transferred to another business. You would create a new ad account in your own portfolio, so export everything first.
Google says your account keeps its own campaign history after unlinking. Shared remarketing lists and cross-account conversion tracking set up at the manager level can stop working, so check those first.
Administrator. In GA4 only Administrators can manage users. Editors have full control of settings but cannot add or remove users.
After exports are complete, the new agency has access and tracking has been checked. Removing access first risks losing documentation or breaking integrations tied to their logins.