The real implications of running Google CSS internally, externally and with multiple partners

Making good business decisions is often as much about justifying a choice as it is in picking the right option. And while the advice in most online articles to work with multiple external CSS partners still remains true, the main reason to justify this option has changed significantly.

Having the latest detailed explanation of the real implications of running various Google CSS options will not just help you choose wisely. It will also make it easier and more convincing when you need to explain the plan to colleagues and senior management.

Some elements of a Google Shopping campaign will be identical whichever route you choose to manage your campaigns. But there can be significant differences in the cost and performance of your adverts depending on which strategy you employ. The easiest way to demonstrate this is to look at each step of the Google Shopping process, and highlight how this differs in each case.

Google CSS Set-Up

To get the best access to the full range of Google Shopping advertising opportunities requires working with a CSS partner (which could be Google) to implement your ads, even if you run and manage your campaigns with an internal team.

The requirements to begin advertising include:

For an internal team, this may be the first attempt at creating a Product Data Feed. Not only are there a number of requirements for this to be accepted, but some of the most common Merchant Center errors are due to data quality.

It’s possible to bring in a consultant to advise on the initial Google Shopping set-up, but this adds an additional cost to the process before you start to add additional sales and revenue to your business.

With one or several external CSS partners (find a partner  they will have set-up and managed large numbers of data feeds. So, you can benefit from their experience in the most efficient and effective ways to create your information, and ensure it meets the standards required.

And a CSS which takes you on as a client will have a shared interest in making your set-up work in the best way to give them the best chance of success in delivering sales for you.

An experienced CSS partner will also be able to quickly spot issues with your website, content and products, based on ensuring compliance for thousands of previous examples. This can save a lot of time, and conversations with support team at Google.

Finally, it’s worth considering which countries you are intending to target for advertising. The legal requirements vary greatly between different European nations. So, if your internal team isn’t aware of the Google Shopping and general product sales laws for every country, it can lead to account suspensions and other issues. An external CSS partner which has scale and reach will also have gained the experience of solving retailer questions and problems in every country they cover, meaning that they know the likely issues you will need to have resolved before they can become problematic.

Bidding & Pricing on Shopping Ads:

Google Shopping ads are provided on an auction basis. This means you need to bid to appear on Google search results pages in the same way you would with Google text ads. The quality and relevance of your adverts play a part, but the bid amount is key to a successful and profitable Google Shopping campaign.

Even internal teams will need to work with a CSS to gain access to all of the features and promotions available via Shopping Ads of Google. 

In the example your product is only presented once by either you through the Google CSS or another CSS partner

All merchants and CSSs working on their behalf will place bids, with the winner paying the next highest price to secure the position.

Whether you add an external CSS partner to your internal team, or you work with multiple CSS providers, it will make no difference to the price you pay for winning the advertising auction. Google will treat all bids for the same offer (the same product from the same merchant) as coming from one source, and discounts the second highest bid made on your behalf rather than increasing the winner price.

This means you will pay the same price after winning a bid whether you work with one, two, or one hundred CSS partners.

This also means that the multiple instances of the same offer won’t appear on one results page. However, working with multiple partners means a great chance of different products potentially appearing in the same ad unit, which increases your brand awareness and the chance of capturing a sale.

The same adverts will also be guaranteed to appear on the comparison website each CSS is required to operate as part of their requirement to become a Google Comparison Shopping Service. For example Working with a CSS which operates a comparison site with a large audience means additional exposure and potential sales for no extra cost.

Most retailers will find that adding multiple CSS partners will continue to deliver incremental improvements in traffic and sales beyond the number you might expect. Brands such as eBay and Nike benefit from the services of 10 or more CSS partners in addition to their internal teams.

Having multiple CSS partners bidding on your behalf means you also benefit from the different approaches and strategies of each provider. The advantage of this increases with the size of your product range as one CSS might use a manual approach to set-up, optimisation and bidding, which requires focusing on a subset of your products. But another of your CSS partners could use machine learning, AI (artificial intelligence) and automation to scale their optimisation across your entire inventory,such as RedBrain.

CSS Account Management:

The three business models for a CSS to work with a client are Self-service, Managed, or a Hybrid of the two. Some providers will specialise in one particular approach, but others may offer a choice depending on your needs.

  • Self-Service is the model for customers confident in the ability of their internal team and capability. The CSS will create the required Merchant Center and Google Ads accounts, and give you access. You’ll be responsible for providing, uploading and optimising your product data, your bidding strategy and other campaign management.
  • With a Hybrid Model, the CSS will take on part of the work. For example, looking after your product feed and letting your internal team handle the campaign management. Or leaving the product data to you, and focusing on optimising your campaigns.
  • Finally, the Managed Service lets the CSS take your product data, optimise and upload it, and manage all of your bidding and campaign strategies.

In each case, Google will invoice the CSS for advertising (which would be Google Shopping as the CSS). That cost will then be passed to you either as part of a monthly retainer, as a cost-per-click with an additional fee for the CSS, or in some cases, on a Cost-Per-Action (CPA) model which only charges you on completion of a sale rather than when someone clicks on your advert.

As an example, Google Shopping EU will operate on a largely self-service basis (although they can offer consultancy when considered appropriate). Buying through Google CSS, you are charged on a cost-per-click basis with a 20% fee added before your bid is placed. This is how the Google CSS funds itself as a standalone business after it was required to split from the parent Google company by an EU Commission ruling in 2017

Other CSS partners can choose their preferred billing model. For example, the RedBrain Managed Service is available on a CPA basis. So, you are only charged for the work when it’s successful in delivering a completed sale. Which means you pay a commission from your incremental profits rather than for advertising.

As mentioned above, the daily management of the bidding and campaign optimisation will vary between CSS partners.


With access to the Merchant Center and Google Ads account you can view all reporting available on both self-service and managed accounts. Using tracking tags will allow you to also get more insight, and share conversion data between Google Ads accounts.

If your CSS opts in to data sharing, their activity will be broken down in the Merchant Centre Comparison Shopping Services activity dashboard. This shows a maximum of five CSSs working on your behalf at any time, with a maximum time frame of 30 days. You can choose your top-five performers, or pick any five who are working with you.

A CSS partner will also report the number of clicks sent to a merchant, and cost charged per click. In addition, they may highlight additional opportunities or areas for improvement. A good CSS partner will work in conjunction with any internal team to ensure both benefit from collaborating on optimisation.

A leading games retailer and RedBrain have worked together since 2017.

“We first started working with RedBrain on their comparison shopping site, and in February we trialled RedBrain’s Shopping Service. Within this trial we received a 30% increase in Google Shopping related sales with no impact to our own campaign. RedBrain have been running a campaign on our behalf ever since.

The team at RedBrain are always extremely alert when it comes to special offers and pre-orders, which can massively impact the amount of sales we make within a certain month.

Since we setup with RedBrain on their Shopping Service, we have gained £100k per month in incremental sales.”

Will CSS Campaigns Overlap?

If you combine an internal team with an external CSS partner, or work with multiple CSS partners, there’s a chance of a small overlap between the efforts of each bidding strategy. But the effect on campaigns will be marginal.

“We gained incremental sales, increased our ROI on our own campaign and gained additional support for Google Shopping by partnering with RedBrain.

If we didn’t have an additional campaign running for us at the same as our own, we would have missed out on £500k in sales.” Nicola White, Head of Performance Marketing at Missguided.

Typically, complimentary CSS strategies will have single percentages of overlap, which can be balanced against the benefits of covering the maximum number of potential customers.

But if you do have concerns, the easiest way to find out is by testing. Working with CSS partners offering CPA billing means there’s no risk in running a trial which will highlight any overlaps in just a few weeks.


There’s very little risk in using multiple CSSs, whether that involves an internal team or purely external partners. In fact there are huge benefits to running with multiple CSS partners especially at a testing phase. Choosing complimentary approaches and CPA billing means that you can benefit from significant numbers of incremental sales without ramping up costs and fees.

The implication of using an internal team for your Google CSS campaigns depends on your business size, scale and strategy. If you have the resources available in-house, and want to increase skills and experience, then it is worth investing the time and money.

But for almost all retailers, it’s beneficial to work with multiple CSS partners. Not only does this mean the best chance of reaching the most potential customers, but it also gives you access to the most experience and data that will likely drive the most incremental sales


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