A practical GA4 migration plan now that Universal Analytics has an end date
Google will stop processing Universal Analytics hits on July 1, 2023. Working backward from that date gives you a migration schedule that keeps a full year of comparison data.
Google announced on March 16 that standard Universal Analytics properties will stop processing new hits on July 1, 2023. Google Analytics 360 properties get three more months, until October 1, 2023. Google's advice is to move to Google Analytics 4 as soon as possible so you build up history before the cutoff.
That is a long runway, and it is tempting to ignore it. Don't. The deadline is not the real constraint. The real constraint is how much comparable data you want to have in GA4 when Universal Analytics goes dark.
Work backward from the year-over-year problem
GA4 and Universal Analytics use different data models, and historical data does not carry over from one to the other. Universal Analytics is built around sessions and pageviews; GA4 is event-based. Numbers will not match even when both are installed correctly, so you can't simply swap one for the other and keep the same trend line.
If you want to compare a month in 2023 with the same month in 2022 inside GA4, GA4 has to be collecting data in that month in 2022. For a business with seasonal peaks, such as a Q4 retail season or a January fitness push, that means the property has to exist before the peak you care about. Setting it up this spring, not in June 2023, is how you get a full year of comparison.
Step 1, create the property and leave Universal Analytics running
Create a GA4 property alongside your current one and keep Universal Analytics collecting. Running both is the point. You will use the old property as the reference while you validate the new one. Google also says properties created before October 2020 are likely Universal Analytics, so check which type you actually have, since a property ID that starts with "UA" is the older kind.
Step 2, list what you rely on today
Before you configure anything, write down what your team actually uses in Universal Analytics:
- Goals and ecommerce events that feed reporting or ad platforms.
- Audiences and remarketing lists shared with Google Ads.
- Custom dimensions, filters and views that someone built years ago.
- Reports that stakeholders open every week.
An old analytics account can easily hold more clutter than value. The migration is a good moment to drop what nobody uses, and the list tells you what has to be rebuilt as GA4 events and conversions.
Step 3, define events deliberately
Because GA4 counts events rather than sessions, the definitions are yours to make. Decide a short list of conversion events, name them consistently, and implement them once, ideally through a tag manager, so web and app share the same names where possible. GA4 is designed to show user journeys across websites and apps, which is the reason to be careful about naming from the start.
Step 4, validate against a source you trust
Compare GA4 against your backend counts for orders, signups or subscriptions, not only against Universal Analytics. Expect differences with the old property, because the two count things differently. What you are checking is that GA4 is stable and directionally right, and that the gap stays roughly constant week to week.
Step 5, export what you need from Universal Analytics
Google has said existing Universal Analytics data should remain accessible for at least six months after the cutoff, and recommends exporting historical data during that window. Decide early what you need to keep, such as monthly traffic and conversion summaries by channel for the last two or three years, and schedule the export well before the deadline rather than in the last week.
A schedule that works
- Spring 2022: create the property, install tagging, and begin collection.
- Summer 2022: define conversions, rebuild essential reports, and validate against backend data.
- Autumn 2022: connect GA4 to your ad platforms and begin comparing with the old property.
- Early 2023: make GA4 the reference for decisions; use Universal Analytics only as a check.
- Before July 1, 2023: complete exports and retire dependencies on the old property.
The takeaway: treat July 2023 as the end of a migration, not the start of one, and put the GA4 property in place this quarter so the first full year of data is waiting when you need it.