Google has confirmed that Customer Match data - specifically customer loyalty data - can now be uploaded via the Merchant API. The documentation update formalises what Google signalled back in March. On the surface it sounds like a plumbing change. In practice, it tightens the connection between your CRM data and the campaigns most likely to act on it.
What Has Actually Changed
Previously, Customer Match lists were uploaded through the Google Ads API or directly within the Google Ads interface. The Merchant API sits closer to the product feed and Merchant Center infrastructure - the same layer that powers Shopping and, critically, Performance Max. The ability to push loyalty data through that channel means it can be integrated earlier in the data pipeline, rather than managed as a separate task in the ads platform.
For advertisers with existing Merchant API integrations - typically retailers managing large product catalogues, pricing, and promotions programmatically - this removes a friction point. Loyalty segment updates can now sit alongside feed updates in the same workflow, rather than requiring a separate process through a different API.
It is also a signal about where Google sees first-party data fitting within its Shopping ecosystem. Customer loyalty data being a named example here is deliberate. Google is not talking about cold prospecting lists. It is talking about the customers you already know, and it wants that data closer to the campaigns that are built around product discovery and purchase intent.
Why This Matters for Performance Max
Performance Max uses audience signals to accelerate learning. It does not target those signals exclusively - it uses them as a starting point to find similar, higher-value users. The quality of what you feed in directly affects how quickly and accurately PMax finds the right people. Loyalty data is arguably the highest-quality signal you have, because it represents people who have already bought from you.
If you are running PMax for e-commerce with a product feed, being able to upload segmented loyalty lists through the Merchant API means you can structure your audience signals with more precision. A segment of repeat purchasers with high average order value is a different input to a broad email list from a newsletter sign-up. PMax will treat them differently, and your campaign results will reflect that.
There is also a bidding dimension. Customer Match lists can be used with Smart Bidding to adjust how aggressively you bid for returning customers versus new prospects. If your margin profile differs between customer types - and for most retailers it does - having clean, up-to-date loyalty data flowing into the account gives Smart Bidding the right inputs to make sensible decisions about where to spend.
The Data Quality Problem This Does Not Solve
Easier upload mechanics do not fix poor data. Customer Match match rates have always been the limiting factor. If your CRM is holding email addresses that are two years old, or phone numbers that were never validated, a more convenient upload route will not improve your match rate with Google's systems. You will still get a large chunk of your list failing to match.
The fundamentals still apply: email addresses work better than phone numbers for matching, hashed data must be formatted correctly, and list freshness matters. If you are pushing loyalty data through an automated Merchant API integration, make sure the pipeline is pulling from a live CRM segment rather than a static export. A stale list uploaded efficiently is still a stale list.
Consent compliance is also non-negotiable. Customer Match data must only include users who have consented to their data being used for advertising purposes. The Merchant API route does not change the consent requirement - it just means that if you have compliance built into your data capture process, you can more easily automate the upload without introducing manual steps that might inadvertently include unconsented records.
How to Structure Your Loyalty Segments
Not all loyalty data is equal, and uploading a single undifferentiated list misses the point. The most useful approach is to create segments based on purchase behaviour. At minimum, separate high-value repeat customers from one-time buyers. From there, you can build segments around recency, product category affinity, or loyalty programme tier if you operate one.
Within PMax, apply your high-value customer segments as audience signals at the asset group level where your campaign structure supports it. If you are running separate asset groups for different product categories, you can align loyalty segments to the categories those customers have bought from. That is a more precise signal than dropping your entire customer base into every asset group.
For bidding, consider using Customer Match lists with Target ROAS bidding to tell Smart Bidding explicitly what a conversion from a known high-value customer is worth. If repeat customers have a materially higher lifetime value than new customers, your bid strategy should reflect that - and it can, if the audience data feeding it is accurate and current.
What Agencies Need to Think About
For agencies managing accounts where the client owns a Merchant Center and operates an e-commerce loyalty programme, this update opens a conversation about data architecture. If the client's CRM and their Merchant API integration are managed by different teams, there is now a case for connecting them. That is a conversation that goes beyond campaign management and into how their data infrastructure supports paid performance.
It is also worth reviewing whether Customer Match is being used at all in accounts where it should be. Many PMax campaigns are running with minimal audience signal input, relying entirely on Google's automated targeting. That works, but it is slower and less precise than campaigns seeded with quality first-party data. The Merchant API route reduces the operational overhead, so the barrier to getting loyalty data into the account is lower than it was.
The broader pattern here is consistent with where Google is heading: first-party data flowing more directly into campaign infrastructure, with fewer manual steps in between. Advertisers who treat their customer data as a strategic input - not an afterthought - are the ones whose Smart Bidding and PMax campaigns will compound performance over time. This update makes that slightly easier to act on.