From 1 October 2026, Microsoft Advertising removes the Max CPC field when you create a new non-portfolio campaign on Maximize Conversions (with target CPA), Maximize Conversion Value (with target ROAS) or Maximize Clicks. Microsoft's own list of what to cap spend with instead is short: budgets, target CPA, target ROAS, conversion value rules and seasonality adjustments. Max CPC survives in exactly two places, per the same announcement: campaigns created before 1 October that already use it keep it, and portfolio bid strategies keep it for new and existing campaigns.
So the working answer is: your daily budget becomes the hard ceiling, your target becomes the steering wheel, and if you genuinely need a click-level ceiling you build the campaign on a portfolio strategy instead. Everything below is the detail, including two claims circulating about this change that Microsoft has not actually made, each remaining cap with a worked example, a migration checklist for before 1 October, and the Conversions API that Microsoft rewrote in the same month.
What actually changes on 1 October 2026
The change was published in Microsoft's August 2026 product news post, dated 31 August 2026, under the heading "Improving performance: Updates to Max CPC for new campaigns". The operative sentence, verbatim:
"This is why, starting October 1, the Max CPC setting will no longer be available when creating new non-portfolio campaigns using Maximize Conversions (with Target CPA), Maximize Conversion Value (with Target ROAS), or Maximize Clicks."
Three things in that sentence get misquoted. The word Microsoft uses is non-portfolio, not standalone. The two Maximize strategies are named with their target settings attached, because since 4 August 2025 Target CPA and Target ROAS are no longer separate bid strategies in the API: they became settings inside Maximize Conversions and Maximize Conversion Value. And it applies at campaign creation, so it is not a retroactive strip of the field.
The date sits on our ad platform deadline calendar alongside the other autumn 2026 changes. It lands the same day as Google's Local Services Ads missed-call billing, and the same day Microsoft starts shipping new API features to REST only.
Who is affected, and who is not
| Situation | Max CPC on 1 October 2026 |
|---|---|
| Existing campaign created before 1 Oct that already uses Max CPC | Keeps it |
| New campaign, portfolio bid strategy | Keeps it |
| Existing campaign, portfolio bid strategy | Keeps it |
| New campaign, non-portfolio Maximize Conversions with target CPA | Removed |
| New campaign, non-portfolio Maximize Conversion Value with target ROAS | Removed |
| New campaign, non-portfolio Maximize Clicks | Removed |
Microsoft's wording on the survivors, verbatim: "Existing campaigns created before October 1, 2026, that already use Max CPC will keep the setting, and Max CPC will remain available for new and existing campaigns using portfolio bid strategies."
Two claims circulating about this change are not supported by the announcement. Microsoft's post says nothing about Target Impression Share. The API reference for TargetImpressionShareBiddingScheme still carries an optional MaxCpc element, and the bulk campaign schema says the field "is only used if the Bid Strategy Type field is set to MaxClicks, MaxConversions, TargetCpa, TargetImpressionShare, or TargetRoas", which puts Target Impression Share outside the three named strategies. That is an inference from schema docs last dated November 2024, not a Microsoft statement.
The Enhanced CPC claim looks wrong outright. EnhancedCpcBiddingScheme has no MaxCpc element at all, and eCPC is absent from the bulk schema list above. Under eCPC you set ad group and keyword bids and Microsoft adjusts them, so there is no campaign-level Max CPC to lose.
Do this now: filter your campaign list by bid strategy and write down which campaigns are non-portfolio Maximize anything. Those are the ones you can no longer clone with a CPC cap after 30 September.
Why Microsoft says it is doing this
Worth reading in Microsoft's own words, because it tells you how the system will behave once the cap is gone:
"In our platform, we see that when advertisers set a Maximum CPC, which overrides advertisers' own CPA/ROAS targets, this provides conflicting instructions to the system and causes advertisers to miss their overall desired outcomes, even when the cap is above average CPC."
The argument is that a CPC cap and a CPA target are two different instructions, and when they disagree the cap wins and the target loses. Treat that as Microsoft's claim: no independent test of it has been published as of 3 September 2026. The company also states that its bidding "continues to allow campaigns to over-achieve on target CPA or target ROAS efficiency, regardless of budget limited status", and calls targets "directional levers" rather than rigid values. That is the opposite of the direction Google took on 17 August 2026, when budget-limited tCPA and tROAS campaigns began optimising to the stated target instead of overperforming it.
Cap one: the daily budget, which is now your hard ceiling
With the CPC cap gone, the budget is the only number in the account that cannot be exceeded on a sustained basis. Microsoft names it first in its replacement list.
Worked example. You are launching a Maximize Conversions campaign with a £40 target CPA and you want to risk no more than £600 in the first fortnight. Set the daily budget to £43. Fourteen days at £43 is £602, and daily spend can run above the figure on individual days while the monthly average holds. Your exposure is bounded even if average CPC lands at £4.50 rather than the £2 you would have capped it at.
The trade: a budget cap limits total loss, a CPC cap limited per-click loss. If a single expensive click can hurt you, the budget alone does not solve that, and you want the portfolio route below.
Do this now: for every campaign you plan to launch after 30 September, set the daily budget at the number you are willing to lose in a day, not the number you hope to spend.
Cap two: target CPA on Maximize Conversions
The target CPA is the control Microsoft wants you steering with. It is not a cap in the arithmetic sense, because individual conversions will cost more and less than it, but it is the number the system optimises the average toward.
Worked example. Your product has £120 of gross profit per sale and your site converts paid search clicks at 2.5 percent. Break-even CPA is £120. Set the target at £70 to leave real margin, and the implied average CPC the system can afford is £70 x 0.025, which is £1.75. You did not type £1.75 anywhere, and that is the point: the CPA target expresses the same ceiling in the units that actually matter to your P&L.
Move the target in steps of 10 to 15 percent and leave a fortnight between moves. Big target jumps re-enter the learning phase and produce the volatility people then blame on the missing CPC cap.
Do this now: calculate the CPA your margin can carry before you open Microsoft Ads, and write it down. Target CPA only works as a cap when it is derived from margin rather than from last month's number.