# GA4 Property Setup Checklist for Marketers

> A GA4 admin checklist for marketers: data retention, internal traffic, unwanted referrals, cross-domain and Google signals settings.

Source: https://mentionx.ai/learn/ga4/ga4-property-setup-checklist  
Author: Dipuck Jones, founder of MentionX  
Updated: 4 November 2026  
Level: Practitioner

**Spend 20 minutes in GA4 Admin before you trust any report: set data retention to 14 months, filter internal traffic, list unwanted referrals and set up cross-domain measurement if you send visitors to other domains.** None of these fix past data except retention, so do them on day one.

> **Key takeaways**
>
> - Data retention for standard properties is 2 or 14 months. Pick 14; it affects explorations and funnels, not standard reports.
> - Internal traffic is defined in tag settings, then filtered with a data filter you test before activating.
> - Unwanted referrals stop payment providers or login domains stealing credit from the real source.
> - Cross-domain measurement keeps one session across domains you own.
> - Keep Admin changes in a shared change log so report shifts can be explained later.

*Checked 4 November 2026 (CET) against Google Analytics Help and Google developer documentation. GA4 menus and limits change, so confirm in your own property. "Our view" marks MentionX opinion. Ledgerline is a fictional company used for illustration.*

## The checklist

| Setting | Where | What to set |
|---|---|---|
| Data retention | Admin → Data collection and modification → Data retention | 14 months (standard). 360 adds 26, 38 and 50 months. |
| Internal traffic | Admin → Data streams → (web stream) → Configure tag settings → Define internal traffic | Your office and VPN IP ranges |
| Data filter | Admin → Data filters | Activate Internal Traffic after testing |
| Unwanted referrals | Tag settings → List unwanted referrals | Payment, booking or SSO domains |
| Cross-domain | Tag settings → Configure your domains | Every domain you own that a visitor passes through |
| Enhanced measurement | Data stream settings | Confirm which automatic events are on (lesson 3) |
| Key events | Admin → Events | Flag the actions that matter (lesson 4) |
| Links | Admin → Product links | Search Console and Google Ads (lesson 15) |

## Data retention: why it matters

Google's help page is explicit: the retention setting does not affect standard aggregated reports, only explorations and funnel reports. If retention is 2 months and you build an exploration for the last quarter, the older weeks are missing. Increasing retention applies to data already collected; reducing it deletes the affected data in the next monthly process. Large and XL properties are limited to 2 months.

## Internal traffic, tested safely

Filters start in a testing state. Leave the Internal Traffic filter in **Testing** for a few days, then compare the **Test data filter name** dimension in an exploration against normal traffic. Only activate once you see it catching the right rows, because active filters permanently exclude data.

## Unwanted referrals and cross-domain

If customers pay on a processor's domain and return to a thank-you page, GA4 may start a new session credited to that processor. Add those domains as unwanted referrals. If your blog and app live on different domains you own, use cross-domain measurement instead, so one visit stays one session.

> **Pro move:** add a "GA4 changes" annotation habit. Keep a dated log of every Admin change in a shared sheet. When the AI Assistant channel or a filter shifts numbers, you will know why.

*Our view:* a property with tidy settings and three key events beats a sprawling one. Resist adding settings you can't explain to a new team member.

Next: [Events and enhanced measurement](https://mentionx.ai/learn/ga4/ga4-events-enhanced-measurement). Or return to the [GA4 for Marketers track](https://mentionx.ai/learn/ga4/ga4-for-marketers).

## Common questions

**What data retention should I choose in GA4?** On a standard property, choose 14 months, the longest option. The setting only affects explorations and funnel reports, but the default 2 months leaves little history to explore.

**Does changing data retention apply to old data?** Increasing retention applies to data you have already collected. Reducing it deletes affected data in Google's next monthly process.

**How do I exclude my own team's visits?** Define internal traffic by IP address in the data stream's tag settings, then activate the Internal Traffic data filter in Admin. Test it first; filters affect data going forward.

## Sources

- Google Analytics Help, [Data retention](https://support.google.com/analytics/answer/7667196)
- Google Analytics Help, [Filter out internal traffic](https://support.google.com/analytics/answer/10104470)
- Google Analytics Help, [Identify unwanted referrals](https://support.google.com/analytics/answer/10327750)
- Google Analytics Help, [Set up cross-domain measurement](https://support.google.com/analytics/answer/10071811)
- All accessed 4 Nov 2026.

## Frequently asked questions

### What data retention should I choose in GA4?

On a standard property, choose 14 months, the longest option. The setting only affects explorations and funnel reports, but the default 2 months leaves little history to explore.

### Does changing data retention apply to old data?

Increasing retention applies to data you have already collected. Reducing it deletes affected data in Google's next monthly process.

### How do I exclude my own team's visits?

Define internal traffic by IP address in the data stream's tag settings, then activate the Internal Traffic data filter in Admin. Test it first; filters affect data going forward.

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Written and reviewed by Dipuck Jones for MentionX Learn. The HTML version of this page: https://mentionx.ai/learn/ga4/ga4-property-setup-checklist