Google's help page for Display Expansion on Search campaigns now states how the feature has been dividing budgets: ads ran on the Google Display Network from unspent Search budget "with a 50% budget allocation applied in the backend." The page carries no publication or update date. It describes "updated options as of October 2026" and says that from February 2027 that fixed setup goes away, replaced by priority tiers and an optional percentage limit that advertisers set themselves.

In Short

For years, Google let Search ads spill onto other websites and apps when the Search budget was not fully spent, and its help page now says a hidden rule kept that spill to half of the budget. In February 2027 that rule disappears, and the split between Search and those other sites will instead follow settings advertisers choose, or Google's defaults if they choose nothing. Anyone running Search campaigns with the Display Network switched on may see money move between Google Search, search partner sites and the Display Network after that date.

What the page says changed

The page, titled "About Display Expansion on Search campaigns" and published in the Google Ads Help Center as article 7193800, opens with a three-part note. "Display Expansion is transitioning to a new channel prioritisation model," it reads. The version of the page reviewed for this article is the English (United Kingdom) edition, which uses British spelling; the US edition carries the same note.

The note divides the feature's history into three stages:

  • Previous setup: "When enabled, Display Expansion automatically delivered ads on the Google Display Network using unspent budget at a similar cost per conversion as Search and with a 50% budget allocation applied in the backend."
  • Updated options as of October 2026: "You can now set priority tiers (high or low) and assign an optional daily budget allocation percentage cap for channels, such as the Google Display Network."
  • February 2027: "Starting in February 2027, search campaigns with Display Expansion will automatically transition to channel prioritisation. Once this takes effect, the current spend allocation setup will go away, and you may see a shift in channel spending between Google Search, search partners and the Google Display Network."

The final sentence of the note gives the configuration that reproduces the old behavior: "To keep your current configuration, you can set the Google Display Network to low priority with a 50% daily budget allocation."

That recommendation had already appeared in October. When Google introduced channel prioritization and budget allocation on October 14, 2026, its blog post and the separate help page on the new controls both suggested a Low priority Display Network with a 50% allocation for advertisers who wanted to keep their existing setup. Neither document explained why 50% was the matching figure. The Display Expansion page now supplies the answer: the 50% was not an analogy but the allocation the system was already applying, without any setting in the interface that exposed it.

How Display Expansion works under the new model

The rest of the page has been rewritten around the new controls. Display Expansion "can help you reach additional potential customers on the Google Display Network using your search campaign settings," according to the page. It can be switched on and managed through channel prioritization account-level defaults or through campaign-level overrides, and advertisers "can also assign priority tiers and set an optional daily budget allocation percentage cap to control Display spend."

Search campaign settings carry over to Display "wherever possible," according to Google. The page lists what that covers:

  • Bidding and targeting, with contextual relevance given as an example.
  • The overall campaign budget, which is observed. The split between Search and Display can be controlled through account defaults or campaign overrides, including a Low priority setting for Display and an optional percentage, which "operates on a best-effort basis to limit daily spend on that channel."
  • Cost per conversion on Display, which "may vary depending on your chosen bidding strategy, priority settings and custom budget allocation."
  • Ads, which are created automatically from the campaign's search ads. Image ads can be added in the "Assets" section under the "Campaigns" tab.

On the distribution of money, the page is explicit that three inputs now decide it. "Google Ads distributes budget to the Display Network based on your campaign's bidding strategy, assigned channel priorities and any daily budget allocation configured in your account or campaign settings," it states. Ads can appear on Google Search and search partner sites when searches match keywords, and on "relevant website pages and apps" on the Display Network.

What the percentage is measured against

Two notes at the bottom of the page define the mechanics. The first says channel prioritization and budget allocation "apply to campaigns using shared budgets (of the same campaign type) and custom campaign experiments," and that "daily budget allocation is calculated as a percentage of your average daily budget on a best-effort basis." The second describes the order of spending under the two Maximize strategies: "For bidding strategies like Maximise conversions and Maximise conversion value, Google Ads prioritises high-priority channels before allocating remaining budget to low-priority channels, subject to any custom budget allocation that you set."

The page does not discuss target-based strategies. The separate channel prioritization page, which the Display Expansion page links to, states that for Target CPA and Target ROAS campaigns that are not limited by budget, priority tiers generally do not change how spend is distributed and only the percentage allocation has an effect. That page also lists restrictions the Display Expansion page leaves out, among them that budget allocation is not supported for Demand Gen and that multi-campaign shared budgets are not supported in experiments.

Setup steps

The page gives two sets of instructions. For a new campaign, the 12 steps run from the Campaigns icon through goal and campaign type selection to "Campaign settings." In the "Networks" section, the advertiser clicks "View network settings" and selects "Include Google Display Network." The next step is new: "In the 'Channel prioritisation' section, assign priority tiers for the Google Display Network (or leave it set to use your account-level defaults) and set an optional daily budget allocation percentage."

For an existing campaign, the nine-step path opens the campaign's settings, expands the Networks drop-down and selects "Include Google Display Network" under "Display Network." Step 8 reads: "Click Channel prioritisation to configure campaign-specific priority tiers or an optional daily budget allocation percentage (or select 'Use account-level settings')."

Both paths make the account default the fallback. A campaign that does nothing inherits whatever the account specifies for that campaign type, and the Google Display Network channel starts at High priority unless someone changes it, according to the channel prioritization documentation.

Performance figures and where they conflict

The page repeats two performance claims, neither of which carries a date range, sample or method. "Search campaigns that have spare search budgets and are opted into Display Expansion can deliver up to 15% more conversions at similar CPA to Search," according to Google. A second figure applies to value-based bidding: advertisers "can expect to find an average of 14% more conversion value for Search, if your core search campaign is using Maximise conversion value or Target ROAS."

The 15% figure appears twice, with different reference points. The first time it is measured against "Search"; the second time, in the "Find the right audience" section, it reads "up to 15% more conversions at similar CPA as the current campaign's CPA." Both are ceilings ("up to") rather than averages, and the 14% conversion value figure is an average without a stated range. Both figures come from Google and have not been independently verified.

The page's description of reach also differs from other Google documentation. It says the Display Network lets ads reach people "on a collection of more than three million websites, videos and apps." Elsewhere in Google's own materials the figure is lower: when Google moved the Display Network under Demand Gen in May, it described that inventory as more than 2 million sites, videos and apps.

There are internal inconsistencies too. In the bulleted list, cost per conversion on Display "may vary depending on your chosen bidding strategy, priority settings and custom budget allocation." In a boxed note further down, the page states: "On average, your cost per conversion on the Display Network should be similar to that on the Search Network." The same note warns that advertisers who expand from Search to Display "may notice an increase in conversions and thus, an increase in daily spend."

Some passages also predate the new controls and were not rewritten. The page still says a Search campaign with Display Expansion "increases your reach with no additional setup" and that "since Display Expansion is fully automated, your ads will be optimised to target across the Display Network with no additional setup." Under the new model, the share of budget Display receives depends on settings that someone has to configure, or on account defaults.

Responsive display ads

A section titled "Use responsive ads to reach more people" describes how creative is produced for Display placements. Responsive ads are "a convenient, all-in-one format that serve across the entire Display Network," according to the page, and they "automatically adjust their size, appearance and format to fit just about any available ad space" using headlines, images and the landing page supplied by the advertiser.

Creation can happen without the advertiser building anything. "If you've uploaded Google Ads image assets, from Search for example, Display Expansion may create responsive display ads automatically with no work required on your part," the page states. That means image assets uploaded for Search, for example image assets that appear alongside text ads, can end up in Display placements as part of an automatically assembled responsive display ad. The page does not say whether advertisers are notified when such an ad is generated or how to stop it, beyond the network opt-out.

What the page leaves out

The help page on channel prioritization lists one consequence of the February 2027 migration that the Display Expansion page does not mention: "GDN will no longer serve on Search campaigns utilizing the Target Impression Share bid strategy." Search campaigns built around impression share goals therefore lose Display delivery entirely rather than moving to the new tiers. The Display Expansion page's instructions and notes make no reference to Target Impression Share.

The page also does not say:

  • how the 50% backend allocation behaved when a Search campaign spent its full budget on Google Search, or whether the allocation was measured against the average daily budget or against unspent budget;
  • when the backend allocation was introduced, or whether it changed over time;
  • whether the February 2027 migration happens on a single date or in stages;
  • whether the migration will set a 50% allocation automatically for campaigns that do nothing.

The last point matters most for accounts that do not touch the setting. The note says the current setup "will go away" and that spending "may" shift. It does not say that Google will write a 50% Low priority configuration into migrated campaigns. Under the channel prioritization documentation, all channels default to High priority, which would put the Display Network on the same tier as Google Search with no percentage limit unless an account default says otherwise.

Why this matters for search advertisers

PPC Land's coverage of the October controls set out how the percentage limit works on a best-effort basis, and Ginny Marvin, Google's Ads Product Liaison, said in an October 16 newsletter that Performance Max advertisers can set Search partner spend to 0%. What was missing from those documents was the baseline. Advertisers who kept Display Expansion switched on had no setting in the interface that showed a 50% allocation was in place.

The disclosure lands in a year in which Google has also reorganized the Display Network itself. Standalone Display campaigns are being folded into Demand Gen, where the Display Network becomes an opt-in channel; Google announced that change on May 26, 2026. Display Expansion is one route by which Search budgets reach Display inventory, and from February 2027 the size of that route will be set by a visible percentage rather than an unstated one.

Is a best-effort 50% the same as the backend 50% it replaces? Google says the new configuration keeps "your current configuration," but its own documentation describes the new limit as a target that daily spend "may occasionally exceed." The page does not say whether the old allocation behaved the same way.

Timeline

Summary

Who: Google Ads, through its Help Center page on Display Expansion on Search campaigns. The change affects advertisers running Search campaigns with the Google Display Network included.

What: The page states that Display Expansion previously applied a 50% budget allocation in the backend when it used unspent Search budget on the Display Network. That setup is being replaced by channel prioritization, with High and Low priority tiers and an optional best-effort daily percentage limit. The page also repeats Google's claims of up to 15% more conversions and an average 14% more conversion value, without stated methods.

When: The page carries no date. It describes options available "as of October 2026" and an automatic transition starting in February 2027.

Where: In the Google Ads interface, in account-level channel prioritization defaults and campaign-level network settings, wherever Search campaigns can opt into the Display Network.

Why: Google is moving every campaign type to one system for ranking and limiting channels. For Search campaigns, the change replaces an allocation that advertisers could not see or adjust with one they set themselves, and it could shift spend between Google Search, search partners and the Display Network for accounts that do not configure it.