What is custom attribution in Meta Ads, and should a B2B advertiser use it?

TofuAnswer by the Tofu team · checked

Three different measuring tapes laid side by side on a white surface.

Usually not, for now. Jon Loomer reported in August 2026 that some advertisers had Custom, a third Meta attribution model next to Standard and Incremental. It makes a Sales campaign optimize on purchase credit from your own attribution model, sent through the Conversions API by you or by Adobe, Northbeam, Rockerbox or Triple Whale. B2B lead gen doesn't fit: Meta doesn't support Lead events for it, and the credit must reach Meta within 48 hours of the purchase. It can suit a SaaS company that sells plans online.

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As of October 2026.

Standard vs incremental vs custom attribution

StandardIncrementalCustom, through a partnerCustom, from your own system
Who decides the creditMeta, inside the click, engage and view windows you pickMeta's models, which predict whether an ad caused the conversionYour partner's attribution modelYour own attribution model
Campaigns it works withMeta lists its windows for website and in-store conversionsSales, Engagement or Leads, converting on Website or Website and appSales objective, optimizing for PurchaseSame as through a partner
Lead eventsYesWebsite leads onlyNoNo
Bid strategyNo limit statedNo bid controlsHighest volume or Highest value onlySame as through a partner
SetupPick windows at the ad setPick Incremental at the ad setTurn on passback in the partner's tool, then wait about 2 weeks for Meta to trainEngineers send AppendAttribution events, then the same wait
CostIncluded in Ads ManagerIncluded in Ads ManagerThe partner's fee; Meta's pages list no fee of their ownEngineering time
Main limit for B2BCounts every form fill, qualified or notFewer reported leads to judge it byPurchase only, built around online ordersCredit must arrive within 48 hours, so it can't wait for a deal to close

For more on the first two, see what Meta's click-through attribution change did to conversions and whether to use incremental attribution for B2B lead gen.

What is custom attribution?

Meta describes it as "an attribution model that optimizes for outcomes as measured in your external analytics tool": instead of Meta's default model, "the ad delivery system directly uses your attribution data to optimize." So yes, it can make Meta optimize on your own numbers instead of its click-through counts, but only inside a Sales campaign.

The data travels as a Conversions API event called AppendAttribution. It points at a purchase Meta already received and adds your credit for each ad click, as a share between 0 and 1 (0.3 for 30% credit, for example), plus the value that share stands for, with the ad ID and time of the click. Rockerbox notes that custom attribution uses only click events for now.

In Ads Manager, the Results column then shows your tool's numbers. Meta calls small differences from your tool "expected and normal" and says to keep judging results there.

When did it arrive, and who has it?

Meta hasn't published a dated announcement, and its help pages say "This product or feature may not be available to you yet." Others describe access differently:

  • Jon Loomer wrote on August 10, 2026 that "some advertisers have a new option when selecting the attribution model": Custom, next to Standard and Incremental.
  • Northbeam calls it a beta. Its setup guide mentions a "broader rollout planned for August 2026," and its FAQ says live optimization is "invite-only."
  • Rockerbox says custom attribution "is open to every advertiser," but the option appears only after Meta has 14 days of good data.
  • Meta's developer guide says that after training, "your Meta account representative will reach out when your CAS is eligible for ad optimization."

They don't agree on who can use it today. If you don't see a Custom option under Attribution model in a Sales ad set, you likely don't have it yet.

Which attribution partners does it work with?

Meta lists four, and you can also build your own connection:

PartnerHow you turn it onWhat the partner says
AdobeAsk your Adobe representative about the Adobe Advertising Connector for MetaMeta gives no other details
NorthbeamThrough its Apex productWorks best with about 50 Northbeam-attributed orders a day; the technical minimum is 10 events in 7 days. Doesn't yet support its Clicks + Deterministic Views model
RockerboxIts DV Relay for Meta product; contact your Rockerbox representativeNeeds a Meta dataset receiving Purchase events; "built for purchase events specifically"
Triple WhaleIts Meta attribution passback integrationMeta links to Triple Whale's quick start guide

HubSpot, Salesforce and other CRMs aren't on Meta's list. Northbeam's pricing page aims at ecommerce brands: its Starter plan, which includes custom attribution through Apex, shows $1,500, and Professional is $3,500 a month.

Can a B2B lead gen campaign use it?

No. Meta's developer guide says "only events for the Sales objective are supported" and lists Lead, Contact, Schedule and SubmitApplication as not supported. Three more rules get in the way:

  1. The default event is Purchase. Meta supports custom events and other standard events, including CompleteRegistration, StartTrial and Subscribe, only "for select advertisers." You ask your Meta representative to turn them on.
  2. There's a 48-hour limit. AppendAttribution events "must be received within 48 hours of the original event." You can't send credit weeks later, when a lead becomes a deal.
  3. It needs steady volume. Meta gives no minimum; Rockerbox says it "works best on accounts with consistent, meaningful daily volume."

If you want Meta to learn which B2B leads matter, send CRM stages back to it instead; see how to send HubSpot or Salesforce lead stages to Meta.

What do you need before you turn it on?

Meta's help pages list these:

  • A supported partner, or your own attribution system with an active Conversions API connection.
  • A new Sales campaign (you can't add custom attribution to an existing one) with Campaign budget, Highest volume or Highest value bidding, and Website or Website and app as the conversion location.
  • A High connection quality rating for your custom attribution source in Events Manager, then training: 1 to 2 weeks of good data on Meta's help page, up to 14 days in its developer guide. Meta emails the source's creator when it's ready.

Then, in the ad set, pick Purchase as the conversion event and Custom as the attribution model. To compare custom ad sets with standard ones, Meta says to use Compare attribution settings or your own tool, not the Campaign Overview table.

When standard attribution is the right pick

For most B2B lead gen on Meta, including Instant Forms. Keep the same windows across campaigns you compare, and judge them by pipeline in your CRM.

When incremental attribution is the right pick

For a website-form Leads or Sales campaign with steady volume, when you think Meta takes credit for leads that would have come anyway.

When custom attribution through a partner is the right pick

When you already use one of the four partners to set budgets across channels and run Sales campaigns for purchases with steady daily volume, such as a self-serve SaaS product with online checkout. Northbeam suggests an A/B test against your current campaign first, then, if it wins, moving at least 20% of budget to it for two weeks or more.

When custom attribution from your own system is the right pick

When you have your own multi-touch model and engineers who can send AppendAttribution events within 48 hours of each purchase. Meta's guide calls a gap of 0 to 5% between its totals and yours normal.

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