Auto-tagging
Auto-tagging is a Google Ads account setting that adds a click ID, the GCLID, to the landing page address, so that Google can tie a later order to the ad click.
How it works
With auto-tagging on, an ad click reaches the site with an extra parameter in the address: the GCLID (Google Click Identifier). The Google tag usually keeps it in a first-party cookie on your domain and sends it with the order. That ties the conversion to the click and its campaign. Auto-tagging is on by default in new accounts.
A redirect that drops the query string removes the GCLID before the tag reads it. Google advises that redirects pass it on to the final landing page. A site that rejects unknown URL parameters may show an error page instead.
To import a phone or CRM order as a click conversion, you need the click ID saved from the visit, usually the GCLID. GA4 keeps Google Ads dimensions, such as keyword and search query, apart from the manual dimensions that UTM tags fill. GCLID and auto-tagging in GA4 explains where (not set) rows in GA4 come from.
Where you see it
- In Google Ads, as an account-level setting: Admin → Account settings → Auto-tagging (
auto_tagging_enabledin the API). - In the landing page address, as
gclid=followed by the click ID.
Example
Example store, not client data.
The tableware shop gets 8,000 ad clicks a month. Of these, 2,000 land on old product addresses whose redirect drops everything after the ”?”. So 2,000 ÷ 8,000 = 25% of paid visits arrive without a GCLID. The shop cannot import a phone order from one of those visits as a click conversion.
Not to be confused with
- UTM parameters — tags you write by hand for source, medium and campaign. They fill GA4’s manual dimensions and do not identify the click.
- GCLID — the identifier itself. Auto-tagging is the setting that adds it.
Right and wrong readings
- Wrong: “Our links carry UTM tags, so we don’t need auto-tagging.” Right: UTM tags name the campaign. To import an offline order as a click conversion, you need the GCLID of that click.
- Wrong: “Auto-tagging is on, so every ad visit carries a GCLID.” Right: a redirect can strip it, so check the address of the final landing page.
Sources
- About auto-tagging — Google Ads Help: on by default, the setting, redirects, error pages. Checked 2 October 2026 (archived copy of 13 June 2026).
- Customer — Google Ads API: an account setting. Checked 2 October 2026.
- Upload click conversions — Google Ads API: on by default; a click ID is required. Checked 2 October 2026.
- Set up consent mode on websites — Tag Platform: click data in the address and in cookies; redirects should keep it. Checked 2 October 2026.
- API dimensions and metrics — Google Analytics: Google Ads and manual dimensions. Checked 2 October 2026.