Your checklist for migrating Google Analytics & Google Tag Manager

By Emma Barnes
11th October 2021

If a website migration is due to happen, one of the things you must take into consideration is how to ensure your data is all going to continue to track.

Carried out incorrectly, a website migration could lead to your data not collecting, becoming polluted or tracking inaccurately. So, I’ve created a downloadable checklist below of a list of items that should be taken into consideration when migrating Google Analytics and Google Tag Manager to ensure accurate and consistent tracking.

This will cover analytics considerations for Universal Analytics (GA3), Google Analytics 4 (GA4) and Google Tag Manager (GTM).

Before determining how to migrate your Analytics, ensure that you’re informed of the type of migration that is happening: are the URLs changing? Is the website structure and page structure changing? Is the website’s purpose changing? Answering these questions will help you plan for your migration.

Download the checklist below or keep reading to find out what you might need to consider with your migration.

Download Analytics Migration Checklist

1. What happens if Google Analytics or Google Tag Manager is incorrectly migrated?

The main risk of not migrating your Google Analytics or Google Tag Manager container is that you will stop collecting data relating to your website and campaigns.

Although historic data will still exist, future data will not be recorded. Fundamentals such as website visits and revenue gained from campaigns could be lost. The secondary risk is that although data will still be recorded, it will not be accurate.

Goals and events are directly related to website URL structure and code implementation, so changes to these may result in loss or inaccurate tracking.

Some common errors that occur alongside mismanaged migration include:

  • Sessions do not track for new pages
  • Self-referrals increase
  • Transactions and revenue are incorrectly attributed to campaigns
  • Goals stop tracing and conversion rate becomes zero
  • Events only partially track or do not track at all
  • Remarketing tags do not get fired
  • Social analytics platforms do not receive data
  • Audiences for paid media do not populate or populate incorrectly
  • Traffic is incorrectly filtered within analytics platforms

2. Google Analytics (GA3 and GA4) site migration checklist

Below is a checklist of migration points that relate to GA3. I would recommend reviewing what applies to your website, making a note of anything that needs changing during migration (e.g. code put on pages) as well as what needs updating a soon as migration happens (e.g. any goal URL changes).

2.1 Google Analytics code migration

For: Both GA3 and GA4

Review how your current GA code is placed on your website (e.g. via Google Tag Manager, code directly on page, via gtag or code injected via a plugin) and ensure it remains on all pages of your website. Include the following considerations:

  • Subdomain and cross domain tracking is also reviewed
  • Ensure (enhanced) eCommerce tracking is maintained as well as pageview tracking
2.2 Event tracking migration

For: Both GA3 and GA4

Event tracking may be sent to Google Analytics via various methods (on page code, tag management, CMS plugins, product integrations, etc.) and can be very sensitive to website changes.

Some events that used to be recorded may not be relevant to the new version of the website, and conversely, your new website may have new functionality that should be recorded as an event.

Create a list of events that need to be migrated across as well as a list of events that will newly need to be tracked. For each event, take a record of how it is tracked (e.g. GTM, via plugin, via integration, etc.) and what changes need to be made in order to preserve.

2.2 Custom event modification migration

For: GA4 Only

Once the event tracing for Google Analytics 4 has been determined, ensure that any custom events (or modified events) are reviewed as the rules or events names may differ post-migration.

2.3 Custom definition migration

For: GA4 Only

Expanding upon event migration, if you track events within Google Analytics 4, you probably have defined custom definitions to go along with them. While migrating events, make a list of the corresponding custom dimensions as well as any user-scoped custom definitions to determine

  • Which ones need preserving or deleting
  • Any new custom definitions that need capturing
  • What changes need making to continue capture of custom definitions
2.3 Goal Migration

For: Both GA3 and GA4

Take a note of all active goals within Google Analytics and how they are recorded. For each goal, keep a record of the following:

  • Does this goal still exist on the new website, if not, disable it
  • Is a goal’s URL due to change? If so, update goals on site go-live
  • Are the goal funnel URLs due to change? If so, update them as soon as possible
  • Update goal events (called Conversion events in GA4) as required

TIP: while you are doing this, review any conversion points you have configured in other platforms (e.g. Google Ads, Facebook Ads, Microsoft ads) and plan to migrate them in a similar fashion.

2.4 Filter Migration

For: Both GA3 and GA4

In Universal Analytics there are number of ways that filters could be affected by a website migration, it is vital to review any current filters to ensure data is collected in a similar way before and after migration. A review of all filters is recommended however, specific filter types to check include:

  • Any filters that include URLs, e.g. inclusion, exclusion, and rewrites
  • Any filters that include your domain name if your domain name is changing
  • Filters that relate specifically to captured data (events, custom dimensions, etc.)

In Google Analytics 4, a migration is less likely to influence the filters used, however it is important to check they are still configured as expected.

2.5 Content and channel Grouping migration

For: GA3 only

Both channel groupings and content groupings make use of rules that determine what group a session or pageview belongs to. These rules may vary depending on the content structure of your website so both need to be reviewed and updated.

  • Update any page URL rules that relate to content or channel groupings
  • Update any page title rules that relate to content or channel groupings
2.6 Audiences migration

For: Both GA3 and GA4

Audiences may differ depending on both the new technicalities of the website as well as the new purpose of the website. Remove any audiences that are no longer required and amend any audiences that need amending post-migration. Examples include

  • Audiences based on interacting with a specific URL
  • Audiences based on the occurrence of a specific Event

TIP: while updating audiences within Google Analytics, take the time to review them in any paid platform as there may be similar discrepancies.

2.6 Other Universal Analytics (GA3) considerations

For: GA3 only

Below are some other Universal Analytics considerations that are less important but may affect your Google Analytics usage:

  • Updating your website URL including default page within the admin section
  • Reviewing the excluded query parameters pre and post migration
  • Updating your site search parameter
  • Updating your referral exclusion list if your domain name or payment providers have changed
  • Amending any custom dimensions or metrics as required
  • Update any segments that use URLs or other dimensions that will have changed post-migration
  • Potentially create a new view to container information relating to new website design metrics
  • Review Google Search Console Link
2.6 Other Google Analytics 4 (GA4) considerations

For: GA4 only

Below are some other Google Analytics 4 considerations that are less important but are worth reviewing:

  • Configuring your domains for cross-domain measurement if website domain has changed
  • List unwanted referrals if payment platforms have changed
  • Potentially create mew data stream for new website


3. Google Tag Manager (GTM) site migration checklist

Once you have reviewed Google Analytics itself, you will probably have a list of considerations for Google Tag Manager to ensure everything is collected correctly. Use your above list to begin to determine your Google Tag Manager migration plan, and collate it with what is relevant for you below

3.1 Google Tag Manager code migration

Ensure Google Tag Manager is on all pages of your website. If it deployed via a plugin, ensure that plugin is updated on the new website. If you migrate to a new CMS, and you previously deployed GTM with a plugin, you need to make accommodations to ensure it is deployed from the new CMS.

3.2 Google Tag Manager trigger migration

One of the most critical parts of Google Tag Manager to review upon migration is the triggers for all tags. These could be whether the trigger itself still respects the new site structure (e.g. if URLs and CSS Selectors have changed, any triggers utilising these need to be updated) or if a different trigger is required for each tag.

Review and amend all triggers to ensure they are correct for the new website and the new data structure. New triggers may be required to be built as well.

3.3 Google Tag Manager Google Analytics event tag migration

As a follow up of the event tracking migration, new tags may need creating, or current tags may need amends. This applies not only to Google Analytics 3 and 4, but to other analytics platforms that use events. If the event names and parameters need changing or if a different trigger needs to be added, this should be done within Google Tag Manager.

3.4 Google Tag Manager variable migration

The majority of variables within Google Tag Manager will not change upon a website migration, but some custom variables may be victim to new site behaviour. Before a migration goes ahead, review your variables.

In particular, dataLayer variables may not exist any longer, CSS selector structure may have changes. Make a list of any variables that need updating, including any that may require additional developer support.

4. Further considerations

There are a vast amount of ‘other related considerations’ to make with regards to Analytics migration, but not specific to just Google Analytics or Google Tag Manager. Here is a list of some considerations below:

  • Test everything in a developer environment
  • Review all custom datalayer implementation pushed to new website
  • Ensure cookie consent is still active on the migrated website and all associated tags still obey the cookie consent
  • Review custom integrations and fields within Google Data Studio that may be affected
  • Review all paid media integrations and analytics with particular attention to goal conversions, retargeting and audiences
  • Review other analytics platform connections
  • Potentially create new Google Tag Manager container for large changes, while referring to the previous container

If you have any further questions regarding how to migration your analytics you can get in touch today. We can create a migration plan for you and your team in a short space of time, as well as help with any parts of the deployment. Perhaps you just have a question about a specific part of the migration, let us know and we’d be happy to chat.

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