Google AI Max Migration: What Changed
Google's AI Max for Search migration is not optional. Starting September 1, 2026, Google began automatically upgrading eligible Search campaigns running Broad Match keywords and legacy Automatically Created Assets to AI Max for Search, rolling out gradually through the month with no opt-out once a campaign's migration date passes, confirmed across Search Engine Land, [TechWyse](https://www.techwyse.com/news/platform-updates/google-ads-ai-max-migration-timeline-search-campaigns), GA Agency, [NateCue](https://www.natecue.com/en/news/google-ads-ai-max-september-deadline/), and [WSI DM Inc's](https://www.wsidminc.com/post/google-locks-in-september-and-february-deadlines-for-ai-max-migration) September 2026 coverage. Google is marketing a +7% average conversion lift from the full AI Max feature set. Independent tracking across more than 250 retail campaigns found the opposite in practice, a 35% ROAS drop after migration, a 42-point gap between the platform's claim and what advertisers are actually measuring.
What actually changes when a campaign gets migrated
AI Max for Search replaces tight keyword-level control with an intent-based matching model layered on top of your existing keywords. Instead of matching strictly against the keyword list you built, the campaign now matches against what Google's model judges the searcher intends, closer to an aggressive form of Broad Match than the keyword targeting most advertisers set up their account to run. Automatically Created Assets, previously an opt-in add-on, get used far more aggressively across ad slots once a campaign migrates. The part that catches most advertisers off guard: migration assigns the campaign a new campaign ID. Any shared or portfolio-level negative keyword list scoped to the old ID stops applying the moment that happens, silently, with no in-account warning.
| Element | Legacy Search campaign | AI Max for Search |
|---|---|---|
| Targeting | Keyword-level, exact/phrase/broad match you control | Intent-based matching layered on top of keywords, broader by default |
| Ad assets | Manually curated, ACA optional | Automatically Created Assets used aggressively across all slots |
| Campaign ID | Original ID retained | New campaign ID assigned at migration |
| Negative lists | Shared/portfolio lists apply as configured | Lists scoped to the old campaign ID stop applying until reattached |
| Search terms report | Continuous history under one campaign | History resets under the new campaign ID |
Google's claimed lift vs what advertisers are measuring
Google's official messaging puts the AI Max feature set, search terms matching, broadened matching, and asset automation combined, at roughly a +7% average conversion lift compared to campaigns not using those features. That is the number circulating in Google's own materials and in early trade coverage. Independent monitoring tells a different story. Agencies tracking more than 250 retail campaigns through their post-migration weeks measured an average 35% ROAS drop against the same accounts' pre-migration baseline, a pattern reported consistently enough across Search Engine Land, TechWyse, GA Agency, NateCue, and WSI DM Inc's coverage that it is not one agency's outlier. Line up the two numbers and there is a 42-point gap between what the platform claims and what advertisers are measuring on their own spend.
A +7% lift claim and a 35% ROAS drop are not two readings of the same number, they are answers to two different questions. Google is measuring incremental conversions from the feature set in aggregate across its own dataset. Advertisers are measuring return against the specific budget and account history they had before migration. Both can be true at once, and that gap is exactly why an account-level audit matters more than trusting either headline number.
Why the gap exists
Three mechanics explain most of it. First, intent-based matching pulls in a wider pool of traffic that clears Google's aggregate definition of a relevant match but converts worse at the account's true cost-per-acquisition than the keyword list it replaced. Second, the new campaign ID breaks negative keyword lists immediately, so search terms an advertiser spent months excluding can leak straight back into the auction, undetected until spend or CPA spikes days later. Third, Automatically Created Assets pushed harder across placements skew impressions toward broader, higher-CPC inventory that inflates volume without improving efficiency, exactly the metric ROAS is built to catch and a raw conversion count is not.
Post-migration audit checklist to run this week
| Check | Why it matters |
|---|---|
| Pull the new campaign ID's search terms report and compare it to your pre-migration list | Intent-based matching can pull in queries your old keyword list would have blocked outright |
| Confirm shared and portfolio negative keyword lists are attached to the new campaign ID | Lists scoped to the old ID stop applying silently, with no in-account alert |
| Compare ROAS and CPA in the 7 days before vs the 7 days after the migration date | Month-over-month comparisons mask the actual before/after delta migration caused |
| Review which Automatically Created Assets are live and pause any off-brand or inaccurate ones | AI Max leans on ACA more heavily than the legacy campaign did |
| Set a temporary tighter budget cap while you audit | Limits downside exposure while intent-based matching is still unproven on this specific account |
| Check directly whether AI Max has migrated this particular campaign yet | The rollout is gradual through September, some campaigns are not touched yet, do not assume |
Who should own this
Nobody at Google is going to flag which of your negative keyword lists just stopped working. Catching a platform-forced migration before it costs a month of wasted spend is exactly what ongoing Paid Media and Analytics work is for, someone who is actually in the account often enough to run this audit the week it happens, not the quarter after. It is the same governance thread as Microsoft killing Max CPC bidding and the broader pattern of platforms narrowing manual control while automation claims outrun advertiser-measured reality.
FREQUENTLY ASKED
What is Google AI Max for Search?
A bundle of Search campaign features, intent-based matching layered on top of keywords, and heavier use of Automatically Created Assets, that Google has been auto-migrating eligible campaigns to since September 1, 2026.
Can I opt out of the AI Max migration?
Not once a campaign's migration date has passed. Google's rollout is gradual through September 2026 with no opt-out after the deadline for a given campaign, per Search Engine Land and TechWyse's coverage.
Why did my negative keywords stop working after the migration?
Migration assigns the campaign a new campaign ID. Shared or portfolio-level negative keyword lists scoped to the old ID stop applying automatically and need to be reattached to the new ID manually.
Does Google's claimed lift match what advertisers are seeing?
No. Google claims roughly a +7% average conversion lift from the full AI Max feature set. Independent tracking across more than 250 retail campaigns measured a 35% ROAS drop after migration instead, a 42-point gap between the platform's claim and advertiser-measured results.
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