LinkedIn Expands Conversions API With 180-Day Attribution and Improved Conversion Matching

LinkedIn Expands Conversions API: Attribution Up to 180 Days and New Conversion Matching Capabilities

In September 2026, LinkedIn updated its Conversions API, adding a 180-day attribution window and new user matching parameters. The changes were included in Marketing API version 202609 and are particularly relevant to B2B advertisers with long sales cycles.

Companies can now more accurately connect qualified leads and other CRM conversions to advertising interactions that occurred several months earlier.

What Is LinkedIn Conversions API?

Conversions API (CAPI) allows events to be sent directly from an advertiser's server or CRM to LinkedIn.

Unlike Insight Tag, which tracks actions taken by website visitors, CAPI can send events that occur outside the website, such as receiving a qualified lead, a change in lead status, or a purchase.

For example, a prospect clicks on a LinkedIn ad, submits an inquiry, and becomes a qualified lead three months later. The CRM sends this event through CAPI, and LinkedIn attempts to match it to the earlier advertising interaction.

These data are used for reporting, attribution, and campaign optimization.

How Attribution Worked Before

An attribution window defines the period after an ad view or click during which a subsequent conversion can be associated with that advertising interaction.

By default, LinkedIn uses 30 days after a click and 7 days after a view.

For B2B companies with long sales cycles, these periods are often insufficient. For example, several months may pass between the first advertising interaction and lead qualification.

LinkedIn already supported a 365-day window for certain conversion types. However, there was no intermediate 180-day option.

This limited the options available to advertisers who needed a longer attribution period without extending it to a full year.

What Changed in September 2026?

LinkedIn introduced two important updates.

1. New 180-Day Attribution Window

Conversion rule settings now offer 180-day and 365-day periods for the following event types:

Lead and Qualified Lead;
Marketing Qualified Lead (MQL);
Sales Qualified Lead (SQL);
Purchase and Add to Cart;
Submit Application.

The postClickAttributionWindowSize and viewThroughAttributionWindowSize parameters allow advertisers to set the attribution periods after ad clicks and views separately.

The new setting is available in all active API versions.

2. New User Matching Parameters

The hashedFirstName and hashedLastName fields have been added to the Conversions API userInfo object.

Previously, the API supported sending first and last names in plain text. Developers can now send their SHA-256 hashes.

Before hashing, values must be normalized, and the result must contain 64 hexadecimal characters.

The fields are available starting with API version 202609.

Why This Matters for B2B Advertisers

The main benefit of this update is the ability to analyze LinkedIn Ads results while accounting for a longer sales cycle.

For example, a SaaS company may receive inquiries in January, qualify leads in March, and close deals much later.

With a short attribution window, some of these events will not be linked to the original ads.

The 180-day window makes it possible to account for more delayed conversions and potentially provides a more complete assessment of LinkedIn's contribution to the sales pipeline.

However, extending the window does not mean an actual increase in leads or revenue. It changes the rules for attributing events that have already occurred to advertising interactions.

Advertisers should therefore compare results with CRM data and account for the methodological change when analyzing trends in CPL, CPA, and ROAS.

Limitations

Long attribution windows are not available for every conversion type. The new name parameters also do not guarantee that every event will be successfully matched to a LinkedIn user.

In addition, configuring an attribution window does not mean that any old CRM event can be sent to the API retroactively. Limits on how old submitted events can be must be considered separately.

For companies with long B2B sales funnels, the update expands their ability to measure advertising results, but its value depends on CRM data quality, correct event transmission, and the chosen attribution model.