How to Set the Right CSS Commission: A Practical Guide

First: CPS Is Not PPC

One of the biggest misconceptions is treating CPS commission as just another marketing cost.

Unlike Google Ads, where advertisers pay for every click regardless of outcome, a CSS partner operating on a CPS model carries the traffic acquisition cost upfront and earns revenue only when an approved order is generated.

The question therefore isn't "How low can we set the commission?" It's "What commission gives the partner enough room to compete in Google's auctions?"

Your COS Should Determine the Commission — Not Your Gut Feeling

Many ecommerce businesses choose commission based on what feels reasonable: 3%, 5%, 8%. Often, there's no calculation behind the number.

Instead, the starting point should be your COS (Cost of Sales ratio) — how much advertising cost is required to generate a certain amount of revenue:

For example, if your Google Shopping campaigns generate €100,000 in revenue on €10,000 of ad spend, your COS is 10%.

If your Google Shopping campaigns are profitable at a 10% COS, your CSS commission should typically operate within a similar range.

Low Commission Doesn't Save Money. It Costs Sales.

Imagine two stores selling identical products: one offers a 10% CPS commission, the other 1%. Both compete in the same Google Shopping auction, but not on equal footing.

Before bidding, the CSS partner calculates how much it can afford to spend based on the expected commission. At 10%, there's room to compete aggressively. At 1%, bidding capacity is severely limited — which means fewer auction wins, less visibility, and fewer orders. The lower-commission store may look cheaper on paper, but it rarely competes often enough to generate meaningful volume.

This is also why "let's start low and raise it later if it works" is a flawed test. With insufficient commission, the CSS partner can't bid competitively, so you get fewer auction wins, less qualified traffic, and fewer orders — not enough data to fairly judge the channel. The conclusion "CSS didn't work" usually just means it was never given a fair chance to compete.

You wouldn't judge Google Ads after testing it on a €5 daily budget. The same logic applies here: the initial commission should already sit within the appropriate range for your category, and only then be optimized based on real performance data.

Typical Commission Ranges

There's no universal rate that works for every business — the right level depends primarily on product margins and overall economics. As a general guideline:

The goal isn't to pay the highest commission — it's to provide enough room for profitable scaling.

These ranges are not fixed recommendations, but practical benchmarks based on typical product margins. Businesses with unusually high or low margins should adjust their commission accordingly.

Why Splitting Commission Between New and Existing Customers Doesn't Work

Many retailers propose something like 15% for new customers and 1% for existing customers. On paper, it sounds reasonable. In practice, it breaks the economics of CSS.

Neither Google nor the CSS partner knows who the customer is at bid time

When a CSS partner places a bid, neither Google nor the partner knows whether the next click will come from a new or returning customer. That information only becomes available after the purchase, while the media cost has already been incurred.

Therefore, bidding decisions must be based on the expected average commission. If a significant share of approved orders receives a much lower payout, the partner's effective bidding capacity decreases — making it harder to compete in auctions from the beginning.

Split Commission Also Hurts New Customer Acquisition

Retailers often introduce split commissions to reduce costs on existing customers while keeping a higher reward for acquisition.

However, because bidding decisions are based on the expected average commission, the effective bidding capacity decreases as soon as part of the traffic receives a lower payout.

With less room to compete in Google Shopping auctions, products win fewer impressions, generate less traffic, and ultimately acquire fewer new customers.

Ironically, a model designed to improve new customer acquisition can end up limiting it.

When Does Customer Splitting Make Sense?

Split commissions aren't a bad idea in general. They work well in channels where customer identity is known before the marketing activity happens, such as email marketing, remarketing, cashback programs, or loyalty platforms. CSS is different, because customer status is only revealed after purchase.

The Bottom Line

The right commission isn't the lowest possible percentage. It's the level that lets your products compete effectively in Google Shopping auctions while keeping customer acquisition profitable.

As a practical starting point:

1. Calculate your target COS and use it as your benchmark.
2. Compare your CSS commission to that COS.
3. Avoid extreme differences between new and existing customer rates.
4. Optimize on real performance data, not assumptions.

Ultimately, CSS commission is not just a pricing decision. It is a bidding strategy.

Set it too low, and you may limit your products' ability to compete long before cost becomes the issue.