Google Ads Changed Bidding on Budget-Limited Campaigns

If you run Google Ads campaigns that are limited by budget and bid to a target cost per action or return on ad spend, their bidding changed between August 17 and August 27, 2026. Google's help pages state the dates, the scope and the mechanism, and they say one thing twice: Google does not adjust your targets or budgets for you. If a capped campaign has been beating its target for months, that over-performance now drifts back toward the target unless someone changes a number.

This post is for advertisers and agencies running Target CPA or Target ROAS campaigns that hit their daily cap. It explains the change in Google's words, lists exactly which campaign types and bid strategies are affected, and gives a five-step review to run on every account. Everything below is from Google's change notice and its FAQ page, read on September 19, 2026. We print no performance figures because Google publishes none and we have not measured across enough accounts to state one.

A campaign is "limited by budget" when it could spend more than its daily budget allows. Before this change, Google's system responded to that cap by bidding more cautiously, so the campaign often came in well under its target cost per action, or well over its target return. That looked like free over-performance, and it was also unstable: raise the budget and the efficiency could shift in ways that were hard to predict.

Now the system optimises to the target you typed in, whether or not the campaign is capped. The cap still limits how much is spent. What changes is the efficiency the spend is bought at: it moves toward the stated target rather than sitting below it. In Google's description, campaigns that were previously overperforming on their bidding targets will see performance trend toward the target if no action is taken.

Two tables, both from Google's pages. The first is by bid strategy, the second by campaign type. A campaign is affected only if it matches a "yes" in both and is limited by budget. Portfolio strategies and shared budgets are included, with adjustments made at the portfolio or shared-budget level; in a portfolio with separate budgets only the constrained campaigns are affected, and in a constrained shared budget the effect is spread across the group.

Google's stated reason is predictability. In its words, the old behaviour, where budget-constrained campaigns may overperform their stated targets, could be confusing and create unpredictable results when budgets were adjusted. By bidding to the target regardless of budget, it says advertisers get more reliable control, predictable scaling and simpler management. The FAQ adds that the auction itself is unchanged, that daily and monthly budgets are still respected, and that the change does not directly increase spend.

Read as an advertiser, the trade is clear. You lose the over-performance a cap used to buy you. You gain a campaign whose efficiency does not move when you add budget, which is what makes demand-led budgeting workable: set the target you actually want, give the campaign headroom, and let daily spend fluctuate. Google's own caveat is that a high daily budget is not a promise it will be spent. This is the same direction of travel as the seasonal controls we covered in our guide to promotion mode: fewer levers, more trust in the target.

1. List every budget-limited campaign on a target-based strategy. Google’s notification went to any account with such a campaign in the last twelve months, so the list is longer than the campaigns capped this week.
2. Compare two windows: the weeks before August 17 and the weeks after August 27, on CPA or ROAS and on conversion volume. Google’s own advice is to wait one to two conversion cycles before judging, so a long-delay account may still be too early on September 19.
3. Choose per campaign: raise the budget so the campaign is no longer limited, tighten the target to the efficiency you were actually getting, or accept the new level because the original target was the real goal. For a strictly fixed budget where you can live with efficiency moving, Google names Maximize conversions or Maximize conversion value as the alternative.
4. Apply the change. Google’s Bid Target Adjustment Tool, available since July 6, 2026, sets the target to recent performance in one click and is reached from the “Review your campaign targets” notification or from the campaign’s bidding settings; Search Ads 360 users find it under “Review bid strategies”. A custom number is equally valid. Smart Bidding reacts to target changes in real time, large or small.
5. Re-forecast. Google says Performance Planner has been updated to the new behaviour and stabilised after August 27, so forecasts made during the rollout should be redone.

Multi-channel campaigns need one extra look: Google says Performance Max and Demand Gen may show a different split of spend across channels after the change, even where the overall effect is the same.

Tell them three things, in this order. First, the campaigns that looked cheap were being held back by their budget, and Google has stopped holding them back; the efficiency they saw was real but was a side effect of the cap, not a setting. Second, nothing has been lost that cannot be set on purpose: if the client wants the $5 CPA they were getting, the target becomes $5, and the campaign will spend less or reach less at that price. Third, the real decision is the one the cap was hiding, which is how much they want to spend at the efficiency they actually need. That is a budget conversation, not a bidding one, and it is the same conversation Microsoft's advertisers are having about the removal of manual max CPC on October 1. Both platforms are removing manual levers in favour of targets, as we noted when comparing their two AI Max products. If you would rather we ran the review across your accounts, our paid media service does it as a standard audit.