LinkedIn Conversions API in 2026: Qualified Leads, MQL and SQL Events, and 180-Day Attribution

What Is a Qualified Lead in the LinkedIn Conversions API in 2026?

A qualified lead, in LinkedIn's terms, is a lead your own business has judged worth pursuing after it arrived, reported back to LinkedIn as a conversion event. LinkedIn's schema defines QUALIFIED_LEAD as "Identified lead as a qualified lead", and adds two finer types from version 202608: MARKETING_QUALIFIED_LEAD, where "The user filled out a lead generation form, and has been filtered by the advertiser to be a marketing qualified lead", and SALES_QUALIFIED_LEAD, the same at sales stage.

The point of sending that judgement back is optimisation. LinkedIn's help page describes the qualified leads optimisation goal as one that "helps provide you with high-quality leads using qualified lead data from your LinkedIn Conversions API (CAPI) or when you connect your CRM". In plain terms, instead of telling LinkedIn to find people who fill in a form, you tell it to find people who become pipeline.

Explain It Like I Am Five

Why Does Qualified-Lead Optimisation Matter for B2B Teams in 2026?

Because lead form volume is a weak proxy for B2B revenue, and optimising for it rewards the wrong people. LinkedIn's own guidance acknowledges the trade-off directly: with this goal "You might see an increase in qualified leads at a lower cost per qualified lead (CPQL), although the overall cost per lead (CPL) might increase as a result." It recommends "focusing on CPQL and the quality of leads generated rather than CPL and total leads."

That sentence is the commercial heart of the change. A B2B team still reporting LinkedIn performance on cost per lead will see this goal look worse on its dashboard while it performs better on pipeline. Switching the optimisation without switching the reporting is how good campaigns get paused.

How Does Qualified-Lead Bidding Work on LinkedIn?

You run a Lead Generation campaign, choose the qualified leads goal, and feed LinkedIn the downstream outcome. LinkedIn's changelog for version 202602 says MAX_QUALIFIED_LEAD "optimizes lead generation campaigns to target high-quality leads using qualified lead data sent from Conversions API (where conversion rule type must be QUALIFIED_LEAD) or CRM data shared from Business Manager." Version 202608 extended that to the MQL and SQL types.

LinkedIn's help page lists the setup when creating the ad set: choose the lead generation objective, select the qualified leads optimisation goal, and "Choose qualified lead conversions from one event source." It also notes that "members who click on your ad are sent to a Lead Gen Form pre-filled with their LinkedIn profile data", so this goal runs on LinkedIn's native forms.

The two event sources, and why you should pick one

LinkedIn accepts qualified-lead signals from the Conversions API, through a direct build or partner integration, or from CRM data connected through Business Manager using CRM Sync, where LinkedIn says "we'll auto-create conversions based on that data" and "it can take up to 72 hours to create the conversion." Its strong recommendation is to use one, not both: "We recommend you don't use both Conversions API (CAPI) and CRM data connected through your Business Manager using CRM Sync qualified lead events". If both exist, "the system automatically associates CAPI events for optimization", and selecting events from both "can result in duplication in reporting and double counting of conversions."

What Are the Timing Rules That Make or Break It in 2026?

Speed of qualification decides whether the signal counts. LinkedIn's help page is explicit: "Qualified leads data must be shared with LinkedIn within 30 days to be included in the optimization of the ad set." The Conversions API itself rejects old events, with a validation message that the "Conversion time should be within 90 days." A lead qualified six weeks later may still be reportable, but it no longer teaches the campaign.

What Changed With Attribution Windows in 2026?

LinkedIn added a 180-day window for long B2B cycles. Its September 2026 note says the postClickAttributionWindowSize and viewThroughAttributionWindowSize fields "now support a 180-day value, in addition to the existing 365-day option" for SUBMIT_APPLICATION, PURCHASE, ADD_TO_CART, QUALIFIED_LEAD, LEAD, MARKETING_QUALIFIED_LEAD and SALES_QUALIFIED_LEAD, and that "This update is available on all active versions."

The defaults have not changed, which matters for anyone who never set them. LinkedIn's schema lists the post-click default as 30 days and the view-through default as 7 days, with allowed values of 1, 7, 30 and 90, plus 180 and 365 for the limited types above. A B2B team with a four-month sales cycle that left the defaults in place is only crediting LinkedIn with a fraction of what it influenced.

Attribution counting is a separate setting. The schema's attributionType defaults to LAST_TOUCH_BY_CAMPAIGN, where conversions "are counted once for each campaign to which they can be attributed", with LAST_TOUCH_BY_CONVERSION as the alternative. Decide deliberately, because the default can count one conversion against several campaigns.

How Do You Set Up the LinkedIn Conversions API for Qualified Leads?

LinkedIn's requirements are three steps: "Create a Conversion Rule", "Associate campaign(s) to the conversion rule", and "Stream conversion events." The rule is created on the /conversions endpoint with conversionMethod set to CONVERSIONS_API, one rule per conversion type, and LinkedIn notes two headers on every request:

X-Restli-Protocol-Version: 2.0.0
Linkedin-Version: {yyyymm}

Each event must identify the person. LinkedIn's validation error lists the accepted options: "SHA256_EMAIL or LINKEDIN_FIRST_PARTY_ADS_TRACKING_UUID or ACXIOM_ID or PLAINTEXT_IP_ADDRESS or GOOGLE_AID or (firstName and lastName) or externalIds or lead". For leads from LinkedIn's own forms, the lead identifier is a Lead Gen form response URN, which ties the qualified outcome back to the exact form submission. From 202609, hashed names also qualify; LinkedIn specifies normalising "to lowercase with no spaces or punctuation" before producing "a SHA-256 HEX-encoded string of exactly 64 characters."

1. Agree the definitions of MQL and SQL with sales before writing any code.
2. Move to API version 202608 or later to use the MQL and SQL types; see our version sunset guide.
3. Create one conversion rule per type with CONVERSIONS_API as the method.
4. Set the attribution window to match your real sales cycle, using 90, 180 or 365 days where allowed.
5. Send the lead URN for Lead Gen form leads where available, plus hashed email.
6. Automate the trigger from your CRM stage change, so qualification reaches LinkedIn within the 30-day window.
7. Choose one event source per ad set, CAPI or CRM Sync, never both.

How Should B2B Teams Report on Qualified-Lead Campaigns in 2026?

Report on cost per qualified lead and pipeline, not cost per lead. LinkedIn has started exposing the metric at account level too: from version 202606 the Company Intelligence API returns costInLocalCurrencyPerPaidQualifiedLead, "Derived as the ratio of total ad spend over the number of paid qualified leads collected from members of the target company within the lookback window." For ABM teams that means cost per qualified lead can be read per target account, not just per campaign.

Two related 2026 changes affect what these campaigns look like. Inbox lead generation campaigns now default to optimised rotation and carry an automatic Not Interested button, covered in our Message Ads changes guide. And every ad account is now capped at 1,000 audience segments, covered in the segment cap and geo guide.

What Are the Common Mistakes in 2026?

• Optimising for qualified leads but reporting on CPL. LinkedIn says CPL may rise while CPQL falls.
• Qualifying leads too slowly. Data shared after 30 days does not feed optimisation.
• Mixing CAPI and CRM Sync events in one ad set, causing double counting.
• Changing the ad set during the two-week learning phase.
• Leaving default attribution windows on a long B2B cycle.
• Staying on an API version older than 202608 and missing the MQL and SQL types.
• Backfilling old CRM history. Events older than 90 days are rejected.

Key Takeaways for 2026

• Qualified leads are your own downstream judgement, sent back to LinkedIn so it optimises for pipeline rather than form fills.
• MAX_QUALIFIED_LEAD arrived in 202602 for Lead Generation campaigns; MQL and SQL types arrived in 202608.
• Qualified-lead data must reach LinkedIn within 30 days to count for optimisation, and the goal needs a two-week learning phase and about five qualified leads in that time.
• Use one event source, Conversions API or CRM Sync, not both.
• A 180-day attribution window joined 365 in September 2026; defaults remain 30 days post-click and 7 days view-through.
• Report on cost per qualified lead and pipeline. CPL may rise while quality improves.

Distk helps B2B teams across India and internationally wire CRM outcomes back into LinkedIn, agree MQL and SQL definitions with sales, and report campaigns on pipeline rather than form volume. If your LinkedIn optimisation still stops at the form, that is the conversation to have. Related reading: LinkedIn lead generation for B2B SaaS in India and choosing a B2B lead generation partner.

Every version number, date, field name and error code in this guide is quoted from LinkedIn's own developer documentation on Microsoft Learn as read on 2 October 2026. LinkedIn updates these pages monthly, so confirm against the live changelog before acting.

Sources

• LinkedIn Marketing API, Recent Marketing API Changes (Microsoft Learn), the September, August, July and June 2026 release notes.
• LinkedIn Marketing API, Conversions API (Microsoft Learn).
• LinkedIn Marketing API, Conversions API Schema (Microsoft Learn).
• LinkedIn Help, Qualified leads optimization goal.
• LinkedIn Marketing API, Versioning (Microsoft Learn).