Last checked against Google’s documentation on 29 September 2026.
Why Target CPA is not spending: the short answer
When a Target CPA campaign is not spending, the bid strategy is usually doing what the target tells it to do. Target CPA sets bids to get as many conversions as possible at the cost per acquisition you chose. If that number is below what conversions actually cost in your auctions, the strategy bids low, loses most auctions, and leaves budget unspent. Google’s own Target CPA help page warns that a target set too low may cause you to forgo clicks that could convert, resulting in fewer total conversions.
The other common causes are a fresh learning period after a change, broken or missing conversion tracking, and low search volume. The fix is almost never “raise the budget”: a campaign that can’t spend what it has won’t spend more because you gave it more. Work through the checks below in order.
The campaign stopped spending after you lowered the target
This is the most common version of the problem. You lower the target to bring costs down, and within a day or two spend, impressions, and clicks fall off a cliff. Two things happened at once:
- Bids fell across every auction. The strategy now expects to pay less per conversion, so it bids less for every search. Searches it predicts will convert at a higher cost than the new target are skipped entirely.
- The strategy started learning again. Google lists a setting change, such as a new target, as one of the triggers of the learning period. Performance is less stable while it recalibrates.
To confirm it, open the campaign’s change history and line up the date of the target change with the date spend dropped. Then compare the new target with the campaign’s actual cost per conversion over the previous 30 days. If the new target is well below what you were really paying, that gap is the cause.
What to do: move the target back toward your recent actual cost per conversion, then lower it again in smaller steps, one change at a time, waiting for the learning period to finish between steps. You edit the target from the campaign’s Settings, under bidding. If the campaign uses a portfolio bid strategy, Google notes the new target applies to every campaign and ad group in that portfolio, so one edit can starve several campaigns.
How low can you set a Target CPA?
Google does not publish a minimum. What it does publish is how it recommends a starting point: the average cost per acquisition from the last 30 days, adjusted for conversion delays. That recommendation is the target the campaign has already proven it can hit. Setting a target far below it asks the strategy to find conversions that may not exist at that price.
A practical way to decide if a target is too low:
- Pull the campaign’s cost per conversion over the last 30 days, and over the last 90 days if volume is low.
- Check how many of those conversions arrive late. If your leads or sales often convert days after the click, recent days will look cheaper than they are until the late conversions come in.
- Compare the target with that real cost. A target far below it is a request for less volume, whether you meant it or not.
- Judge any new target over a long enough period. Google’s guidance on measuring Smart Bidding performance suggests a month or at least 50 conversions, and warns that some conversions take days or even weeks to be reported.
If the business truly can’t afford the current cost per conversion, lowering the target is the wrong lever. The fix is upstream: better search terms, better conversion rate on the landing page, or narrower targeting.
How long the learning period lasts
Google says it can take a few conversion cycles, typically one to two, for a bid strategy to calibrate after a change. It can be faster when there is plenty of conversion data. The length depends on three things: how many conversions the campaign gets, how long your conversion cycle is (the time from click to conversion), and the bid strategy itself.
The triggers are a new bid strategy, a setting change (a new target is one), and a composition change, such as adding or removing campaigns or keywords. The bid strategy shows a Learning status while this happens. Google’s bid strategy statuses page explains each status. Google also advises allowing one to two conversion cycles after a major bidding or budget change before making further adjustments. Every edit restarts the clock, so a campaign that has its target changed every few days may never settle.
Other reasons smart bidding stops spending
If the target hasn’t changed and spend still dropped, check these in order:
- Conversion tracking. Target CPA optimizes to conversions. If the tag stopped firing, or the conversion action was set to secondary, the strategy loses its signal. A Misconfigured status with a conversion setting issue points here. See what to do when conversions drop to zero.
- Limited status. Hover over the bid strategy status. “Inventory” means the campaign is limited by available search volume. “Bid limits” means maximum or minimum bid limits are stopping it from bidding freely.
- Narrow targeting or too few keywords. Exact-match-only keywords, a small location, or a short ad schedule can leave too few auctions for the strategy to work with.
- Rank losses. Look at Search lost IS (rank). A strict target lowers bids, and that shows up as impressions lost to Ad Rank. Our guide to lost impression share: budget vs rank explains how to read it.
- Disapproved ads or paused ad groups. Easy to miss after an edit or a policy review.
The August 17, 2026 change for budget-limited campaigns
Google’s page on changes to target-based bid strategies says that on 17 August 2026 it updated its bidding systems so that Target CPA and Target ROAS campaigns with a “Limited by budget” status deliver performance closer to the targets you set. Before that, some of these campaigns beat their targets. Now they optimize nearer to the target itself. Google says it will not change your targets or budgets for you, and the page offers no opt-out.
This change affects campaigns that are limited by budget, not campaigns that can’t spend. But it matters here because the fix for either problem is the same: set the target at the cost you actually want. Our guide to the August 2026 Target CPA and ROAS change covers the details and the Bid Target Adjustment Tool.
Should you switch to Maximize Conversions or Maximize Clicks?
First, a naming note. Google says “Maximize conversions with a Target CPA” and “Target CPA” work in exactly the same way, and that starting in June 2026 it is relabelling the strategies. Removing the target is what changes behaviour.
| Option | What it does | Use it when |
|---|---|---|
| Keep Target CPA, raise the target | Bids more per auction while still steering toward a cost per conversion | You have steady conversions and a realistic cost you can afford |
| Maximize Conversions, no target | Sets bids to get the most conversions while spending the budget | Spend matters more than cost per conversion for a while, or you need data |
| Maximize Clicks | Gets as many clicks as possible within budget, with an optional max CPC bid limit | Conversion tracking is missing or there are too few conversions to learn from |
Maximize Conversions will spend more reliably, but cost per conversion can rise, so watch it closely for the first conversion cycles. Maximize Clicks doesn’t optimize for conversions at all. Treat it as a way to restart traffic, not a long-term answer for a conversion-driven account. Any switch is a new strategy, so it starts a new learning period.
A step-by-step fix
- Check change history. Did the target, strategy, keywords, or campaigns change right before spend fell?
- Check the bid strategy status: Learning, Limited (and why), or Misconfigured.
- Confirm conversions are still being recorded and the right action is primary.
- Compare the target with the actual 30-day cost per conversion, allowing for conversion delay.
- If the target is too low, move it back toward the real cost, then lower it in small steps.
- Check Search lost IS (rank) and the keyword and targeting footprint.
- Only switch strategy if the target cannot be made realistic, and expect another learning period.
Boxoo’s budgets and bidding agent checks this every day. It compares each campaign’s spend with its budget, reads the bid strategy status and recent changes, and files a case with the evidence when a campaign stops spending. Where the fix is a budget or bid change it prepares it for you, and nothing changes in the account until you press Apply. Other fixes come as exact steps.
Run a free Google Ads audit to see whether any of your campaigns are held back by their targets.
