Mid-July 2026, Google pulled the plug on four attribution models in Google Ads: first-click, linear, time-decay, and position-based. New conversion actions can no longer use any of them. By September, every conversion action still running on one of those models gets automatically migrated to data-driven attribution — no opt-out, no rollback.
Google cited adoption rates as the reason. According to Search Engine Journal's reporting on Google's stated rationale, fewer than 3% of conversions in Google Ads used these four models. That sounds like a minor housekeeping update. If your account is in that 3%, it isn't.
What data-driven attribution actually does
Data-driven attribution (DDA) uses machine learning to assign fractional credit across every touchpoint in the path to conversion. Unlike time-decay — which gives more credit to touches closer to the conversion moment — or position-based, which hardcodes fixed weights to the first and last interaction, DDA adjusts dynamically based on what's actually working in your specific account.
In practice, DDA tends to distribute credit more broadly. Mid-funnel keywords that position-based models shortchanged often get more weight under DDA. For accounts that have been running position-based attribution, the shift can look like performance changed when it's actually attribution that changed.
The bidding implication is the one that matters
Smart Bidding optimizes toward whichever attribution model is assigned to each conversion action. If your Target ROAS campaign is optimizing toward a conversion action using position-based attribution, the algorithm is bidding based on position-based credit assignments.
Switch to DDA and the algorithm's view of what's working shifts — sometimes in ways that affect bid decisions across the whole account. This isn't necessarily a problem. DDA is generally the more accurate model when you have sufficient volume. But the transition can produce ROAS movements that are hard to interpret without knowing which conversion actions changed models and when.
That's why you want to control the migration timing, not hand it to Google's September auto-run.
The volume requirement that catches people
DDA works best with enough data. Google's general threshold is around 300 conversions per conversion action in the trailing 30 days. Below that, the model doesn't have enough signal to distinguish high-value touchpoints from noise. For high-volume accounts — large e-commerce brands, high-spend lead gen — this usually isn't a problem. For secondary conversion actions with lower frequency, DDA in practice may behave more like last-click even though it carries the data-driven label.
The four deprecated models were sometimes chosen precisely by accounts that couldn't hit DDA's volume requirements but wanted something more nuanced than last-click. September auto-migration doesn't solve that underlying problem. It just picks DDA regardless.
If you're running a conversion action below that volume threshold, last-click is the remaining alternative. It's not sophisticated, but it's predictable.
What the mid-July change actually means
The mid-July cutoff was about selectability. You can no longer choose first-click, linear, time-decay, or position-based when creating or editing a conversion action. Conversion actions already on those models kept running on them — until September.
From September onward, those conversion actions migrate to DDA automatically. After that, only two attribution models exist in Google Ads: data-driven and last-click.
What to do before September
Review which attribution model each of your conversion actions is currently using. If anything is still on one of the deprecated models, the question isn't whether to migrate — it's when.
Migrating now gives you one concrete advantage: you pick the date. A self-initiated migration lets you establish a clean before/after comparison window for reporting. When Google runs the auto-migration in September, you get no anchor date. Any metric shift that follows — ROAS, CPA, conversion volume — becomes harder to separate from actual performance changes.
For accounts already on DDA, this announcement changes nothing operationally. The useful check is volume: confirm each high-priority conversion action is clearing the 300-conversion threshold. Any action below it may be working differently than the DDA label suggests.
Understanding how attribution setup, conversion action configuration, and Smart Bidding signals connect across your account is what the free Gromerce audit covers. It takes about three minutes.
The change is mandatory. The question is whether you know about it before it happens.
Sources: Search Engine Journal, Search Engine Land, July 2026
