How to audit Paid Search in GA4, step by step

Open Traffic acquisition and narrow it to Paid Search. Add Session source / medium, then Session source platform, as a second column, and list the campaigns with Session campaign. Read the rule GA4 applied in Admin under Channel groups, then confirm auto-tagging and the Google Ads link. If a row surprises you, a tag usually put it there.

You need GA4, with Editor access for the custom group at the end, and admin access in Google Ads for the auto-tagging check. Half an hour covers it. The goal is to know what sits inside the row before anyone quotes it in a meeting.

Step by step

1. Open Traffic acquisition. It groups visits by Session default channel group out of the box, so Paid Search is already a row. Menu path: GA4 > Reports > Acquisition > Traffic acquisition.
2. Narrow the table to Paid Search. Build a filter on Session default channel group and pick Paid Search as its value. Menu path: + Add filter > Dimension > Session default channel group > Dimension values > Paid Search > OK > Apply.
3. See which sources fill the row. Add Session source / medium as a secondary dimension. Expect google / cpc, plus any other search engine you tag with a paid medium. Menu path: the add button next to the dimension drop-down > Session source / medium.
4. Split auto-tagged clicks from hand-tagged links. Swap the secondary dimension for Session source platform. Google Ads marks traffic from Google Ads activity, and Manual marks the rest, which inside this row means hand-typed tags. Menu path: the same add button > Session source platform.
5. List the campaigns. Switch the main dimension to Session campaign and keep the filter. Search campaigns belong here, and Shopping or Performance Max campaigns should not appear at all. If one does, auto-tagging is likely off and hand tags decided its row. Menu path: the dimension drop-down > Session campaign.
6. Read the rule GA4 applied. The default channel group cannot be edited, but Admin lists it. For Google Ads clicks, GA4 reads the network and campaign type; for tagged links, a search site source plus a paid medium. Menu path: Admin > Data display > Channel groups.
7. Check the Google Ads link. Google says linked data reaches GA4 reports within 48 hours. Clicks from an unlinked account can still show as google / cpc, while their campaign fields read (not set). Menu path: Admin > Product links > Google Ads links.
8. Confirm auto-tagging. With it on, GA4 takes source and medium from the auto-tagged values, even where your own tags say otherwise. Menu path: Google Ads > Admin > Account settings > Auto-tagging > Tag the URL that people click through from my ad > Save.
9. Test that the click ID survives redirects. Paste a landing page URL from Google Ads into your browser without loading it. Add?gclid=TesTER-123, press Enter, and check the page loads with the parameter exactly as typed. Menu path: Google Ads > Landing pages, in the page menu on the left.
10. Split brand from generic search, if you want to. Create a custom group from a copy of the default. Add a channel that needs both Default channel group Paid Search and a campaign name containing your brand word. Drag it above Paid Search, because traffic lands in the first channel it matches. Menu path: Admin > Data display > Channel groups > Create new channel group > Add new channel > Save channel. Then Reorder > Apply > Save group.

A worked example

For illustration, take a shop with four auto-tagged Google Ads campaigns and two hand-tagged links. Here is where GA4's rules usually send each one.

For illustration, the Paid Search row now holds two real campaigns and one newsletter dressed up as an ad. It also misses a real search ad, which one word in its campaign name sent to Paid Shopping. Step 4 unmasks the newsletter, because its Session source platform reads Manual, not Google Ads. Step 5 cannot see the stray ad, so look for it under a Paid Shopping filter instead. With the custom group from the last step, the two real campaigns would also split into a brand row and a generic row.

Now one store's real export, 1 January 2024 to 21 August 2026. On its Channels sheet, Direct holds 57.7% of revenue in last click, first click and touched views alike. Direct is where a visit goes when GA4 can read no source, and no paid row can claim it back. A search click that lost its click ID to a redirect can sit in that pile. That is why step 9 earns its place before any filter.

What to check when the report looks wrong

• Paid Search is empty while Google Ads shows clicks. Google's troubleshooting page names four causes: no link, a link under 48 hours old, auto-tagging off, and a click ID lost in redirects. Work through them in that order.
• Session campaign reads (not set) on google / cpc lines. The clicks carry a click ID, but the account behind them is not linked. Link it under Product links and look again two days later.
• A paid source you know sits in Paid Other. Its medium looks paid, but its source is not on GA4's lists of search, social, shopping or video sites. Retag it with a source GA4 knows, or give it a channel of its own in a custom group.
• The same google / cpc turns up in several rows. That is expected. Auto-tagged Google Ads clicks usually share that source and medium, and GA4 then splits them by network and campaign type. Tell them apart with Session campaign, not with source / medium.
• Paid Search revenue differs between reports. Traffic acquisition credits sessions with paid and organic last click. Key event reports follow your attribution model. Both are right about different questions.
• History changed overnight. Someone probably edited a custom channel group. Google says custom groups apply to reports retroactively, so check the group's definition before you trust a sudden jump.

What to do this week

1. Run the click ID test on your three busiest landing pages. Pass: each page loads and?gclid=TesTER-123 stays exactly as typed. Fail: a page errors or the parameter changes, so ask your developer to keep URL parameters through redirects.
2. Write down what your Paid Search row holds. List one line per source / medium and per campaign, from steps 3 to 5. Pass: every line is a search ad you run. Fail: anything else, such as a newsletter tagged google / cpc, so fix its tags now, since new tags only fix new visits.
3. Decide on a brand split. Pass: you built the custom group, and its brand channel shows in Traffic acquisition when you pick the group as the primary dimension. Fail: brand and generic search still share one row, so a loyal customer's click and a stranger's click get judged as one.

Check the homework. Your GA4 Attribution paths export already holds the evidence. Causality Engine reads that one file and shows what each channel caused next to what last-click gave it, in 1 to 2 minutes, for €99 once (excluding VAT), refundable within 30 days. Check the homework

Sources, 1 October 2026: Traffic acquisition report (Google); Default channel group (Google); Custom channel groups (Google); Connect Google Ads to Google Analytics (Google); Missing Google Ads data in Google Analytics property (Google); About auto-tagging (Google); Traffic-source dimensions, manual tagging, and auto-tagging (Google); Scopes of traffic-source dimensions (Google); User acquisition report vs. Traffic acquisition report (Google); Google Ads campaigns performance report (Google).

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