If you create a new Search campaign in Google Ads today, AI Max is already ticked.
Google's own help page says it plainly: "New Search campaigns have the AI Max feature turned on by default." That single line changes the job of setting up a campaign.
Until this year, the keyword list was the fence. You chose exact and phrase match, you added negatives, and the campaign stayed inside the fence. AI Max removes most of the fence and replaces it with a set of controls that sit elsewhere in the account.
Most of those controls are empty when you start. So the practical question for a UK business putting money into Search in late 2026 is which of them to fill in before the first pound is spent. This article is that list.
What AI Max in Google Ads actually does
AI Max is three features bundled under one switch, and all three are on when the switch is on. Google describes it as an optimisation layer inside a normal Search campaign, not a new campaign type.
The first is search term matching. Google's feature guide says it "expands reach using broad match and keywordless technology." In practice your exact match keyword for "commercial epc assessor northampton" becomes a hint, and Google serves on queries it decides are related.
The second is text customisation, which used to be called automatically created assets. It writes headlines and descriptions per query using your existing ads, your landing page copy and generative AI.
The third is final URL expansion. Google will "send traffic to the most relevant URLs on your website when it's likely to result in better performance." It needs text customisation on, so that the generated copy matches whichever page Google picks.
Each of the three has its own toggle at campaign level, and search term matching can also be switched off per ad group.
Where things stand in October 2026
AI Max left beta in April 2026, and since then Google has been moving existing campaigns onto it whether or not the advertiser asked. The announcement page confirms the April date and the current performance claim: an average of 7% more conversions or conversion value at a similar CPA or ROAS, from Google's internal data for non-retail advertisers.
When AI Max was announced in May 2025, Search Engine Land reported the figure as "up to 14%." A year later the headline claim is half that.
On 1 September 2026 Google began auto-upgrading any Search campaign that used automatically created assets or the campaign-level broad match setting. PPC Land's write-up of the 5 August email notes that broad match campaigns got search term matching only, while campaigns with automatically created assets got text customisation too.
Dynamic Search Ads were due to go the same way, but Google's DSA upgrade post now says that migration is delayed to February 2027. You cannot create a new DSA campaign in the meantime.
So the position is: new campaigns default to AI Max, old broad match and ACA campaigns have been moved already, and DSA has four months left. If you run Search ads in the UK, you are on AI Max or about to be.
What the independent numbers look like
The widest independent dataset comes from Smarter Ecommerce (smec), an Austrian campaign automation firm, and it tells a messier story than Google's average.
Smec's analysis of more than 250 retail Search campaigns, covered by Search Engine Journal in March 2026, found a median conversion value uplift of 13% alongside a median CPA increase of 16%. ROAS ranged from 42% above baseline to 35% below, and only 22% of campaigns landed near their original target.
"AI Max behaves more like a volume expansion layer than a pure efficiency optimization." Brooke Osmundson, Search Engine Journal
The same smec dataset showed where the extra traffic comes from. Of the AI Max impressions analysed, 80% were expansions from exact match keywords and 19.5% from phrase. Broad match contributed 0.38%. The advertisers who thought they had the tightest control were the ones being widened most.
A later smec series, reported by PPC Land in August 2026, tracked 383 million EMEA ecommerce impressions from January 2025 to July 2026. Exact match's share of impressions fell from near 100% to about 71%, with two thirds of the shift happening in the final four months.
The same article records a Monks test from August 2025 in which 99% of AI Max impressions across roughly 30,000 search terms produced no conversion. That is one test, on one account, and Google's product has moved on since. It is still the clearest picture of what an unfenced campaign does with its first month of budget.
None of this says AI Max is bad. It says the extra conversions cost more than your baseline keyword traffic, the spread between winners and losers is wide, and what decides which side you land on is the set of controls you configured before switching on.
AI Max feature versus the control you have
The table below maps each AI Max behaviour to the control that limits it, where that control lives, and the cap Google publishes. All of it is from Google's AI Max feature page, the AI Max FAQ and the brand settings page.
| AI Max behaviour | Control available | Set at | Published limit |
|---|---|---|---|
| Matches queries beyond your keywords | Negative keywords (respected with AI Max on) | Ad group, campaign, account | 1,000 account-level; 5,000 per list, 20 lists |
| Matches queries mentioning other brands | Brand exclusions | Campaign | Not stated |
| Matches generic queries you did not want | Brand inclusions (campaign serves only on listed brands) | Campaign or ad group | Not stated |
| Matches queries from the wrong place | Locations of interest | Ad group | Not stated |
| Sends clicks to pages you did not choose | URL exclusions | Campaign | Not stated |
| Misses pages you want it to use | URL inclusions | Ad group | Not stated |
| Rewrites headlines and descriptions | Text customisation toggle; pinning (not respected if a different URL is chosen) | Campaign | n/a |
| Expands matching at all | Search term matching toggle | Campaign, then per ad group | n/a |
Two things stand out. The brand controls are the only way to stop AI Max spending your money on a competitor's name, and Google's brand settings page confirms exclusions "will be prioritised over brand inclusions" if the two overlap. And negative keywords still work, but they only stop what you have already thought of. AI Max will find queries you never imagined.
The pre-flight checklist
Do these in order, and do them before the campaign goes live. On an auto-upgraded campaign, do them today, because the matching is already running.
Build an account-level negative keyword list. Google's account-level negatives apply across Search, Shopping and Performance Max, with a cap of 1,000 terms. Put the obvious waste here: "jobs", "careers", "salary", "free", "course", "training", "diy", "how to". Then add your own brand variants if a separate brand campaign exists, so AI Max cannot cannibalise it.
Build a competitor negative list and apply it, or use brand exclusions instead. JumpFly's Charlotte St. Pierre, writing on negatives in AI Max, recommends negating competitor terms when spend is high and conversions are zero. Brand exclusions do the same job and catch spellings and languages you would miss.
Decide on brand inclusions. If this campaign exists to defend your own name, add a brand inclusion so it "will only serve for queries associated with the brands you select." If it is a generic campaign, leave inclusions empty, because an inclusion will cut off every non-brand query.
Set URL exclusions before final URL expansion runs. Exclude the careers page, the blog, the privacy policy, the "about us" page, any page with a tracking template that breaks on dynamic URLs. Common Thread Collective's September migration note records 404 errors from incompatible templates as the first thing to check.
Fix conversion tracking so it records qualified leads, not form fills. AI Max expands towards whatever the Conversions column rewards. If that column counts every contact form submission, it will find the cheapest form submissions on the internet. Google's offline conversion import FAQ says the best practice is to "choose either qualified lead or converted lead as your conversion goal," uploaded at least daily, within the 90-day GCLID window.
Check the bidding strategy. Google's FAQ states that search term matching "will not work with manual CPC bidding." If you are still on manual bids, AI Max's main feature is doing nothing, and you should decide whether to move to a target CPA or leave the switch off.
Check the budget is not capped. The feature page says "AI Max won't be effective if campaigns are limited by budget." A £15 a day campaign that is already limited will not get smarter, it will spread the same £15 across more queries.
Book a search terms review for day 3, day 7 and then weekly. The search terms report now shows "AI Max" as a match type with a source column for broad match expansion versus keywordless matching. The first week tells you more than the next month will.
Most of this list is work in account settings, not in the campaign. AI Max moves control from the keyword list to those settings, and if they are blank the campaign has no fence at all.
Which switches to leave off at the start
For a UK lead generation account, our starting position is search term matching on, text customisation off, final URL expansion off. The two creative features go on only once the first month of search terms looks clean.
Search term matching is the feature that generates the extra volume, so it is the one worth testing. Text customisation rewrites your copy from landing page text, which is fine for an ecommerce category page and a problem for a solicitor or a financial adviser whose wording has been checked by a regulator. It raises the same question as an agency using AI to write your SEO content: someone still has to check what the model produced before it goes live. Google added text guidelines and legally required disclaimers in 2026 to address this, but the simpler answer for a regulated firm is to leave it off.
Final URL expansion is the riskiest of the three for a small service site. A plumber with twelve pages has nothing to gain from Google choosing between them, and something to lose if a click lands on the "join our team" page. If you turn it on, do it only after the URL exclusions in step four exist.
The order also protects your reporting. With one feature on, a change in CPA has one explanation. With all three on from day one, you cannot tell which of them moved the number.
What the weekly review looks for
The review takes twenty minutes and answers three questions: which new queries are spending, which have converted, and which landing pages the campaign chose.
Filter the search terms report to the AI Max match type and sort by cost. Anything with meaningful spend and no conversion after a week goes into the negative list, as a phrase match negative where the intent is clearly wrong and as an exact negative where only that one query is the problem. Smec's data shows the expansion is heaviest from exact match keywords, so look hardest at the ad groups you thought were safest.
Then open the landing pages report and look at the "Selected by" column. If AI Max is sending traffic to pages you did not build for paid clicks, add them to URL exclusions. Do this even if the page converted once. A single conversion from the blog does not justify the next hundred clicks.
Finally, compare the AI Max rows against the keyword rows on cost per qualified lead, not cost per form fill. If the expanded traffic is 16% dearer per lead, which is roughly what smec saw across retail, that is a business decision: it may be worth paying for volume, or it may not. It is only a decision you can make if the conversion action means something.
The rule we apply
The deciding question for any account is simple: does the negative list and the conversion action exist before the switch is flipped, or after? Before, and AI Max is a volume test with a known downside. After, and it is Google spending your budget to show you what the fence should have been. Setting those controls before launch is part of what you pay a UK Google Ads agency to get right.
If you want a second pair of eyes on an account before or after the September upgrade, our paid media team runs this pre-flight as a fixed-scope piece of work. Get in touch and tell us which campaigns have already been moved.