16th October 2026
Voucher and cashback publishers can generate substantial revenue for ecommerce affiliate programmes.
They can also create one of the biggest challenges in affiliate marketing: understanding how much of that revenue is genuinely additional.
Imagine an ecommerce brand reporting £200,000 in monthly affiliate revenue.
Of that, £140,000 comes from cashback and voucher publishers.
On paper, the programme looks successful. Sales are being tracked, publishers are earning commission and the affiliate channel appears to be contributing significantly to overall revenue.
But there is a question the headline figures cannot answer:
How many of those sales would have happened without the affiliate interaction?
Some customers may have discovered the brand through a cashback platform. Others may have chosen it over a competitor because of an exclusive offer.
But some may already have been at checkout, ready to purchase, before searching for a discount code and clicking an affiliate link.
These journeys create very different levels of commercial value.
At Conversion Digital, we don’t believe voucher and cashback affiliates should automatically be considered either good or bad.
We believe they should be evaluated on the value they actually create.
Here’s how ecommerce brands can do that.
Affiliate incrementality is the additional revenue, profit or customer activity generated because an affiliate interaction occurred, compared with what would likely have happened without it.
It is different from attribution.
Attribution asks which publisher receives credit for a sale.
Incrementality asks whether the publisher actually helped create additional commercial value.
Consider two customers.
Customer A discovers a retailer through a cashback website, compares several alternatives and chooses the retailer because of the cashback offer.
Customer B arrives at the retailer through branded Google search, adds products to their basket and then visits a voucher website immediately before completing the purchase.
Both transactions might be attributed to an affiliate publisher.
However, their incremental contribution may be very different.
The challenge is determining that difference using evidence rather than assumptions.
For a wider explanation of attribution, customer journeys and controlled testing, read our guide to affiliate marketing incrementality.
Voucher sites can generate incremental sales, but their value depends on how customers discover and use the offers.
A voucher publisher can genuinely influence a purchasing decision.
For example, a consumer might be comparing two fashion retailers offering similar products.
An exclusive discount promoted by a voucher partner could make one retailer more attractive and influence the final purchase.
The voucher publisher may have helped win a sale that would otherwise have gone to a competitor.
But another customer might already have decided to buy from the retailer.
They reach checkout, notice a promotional code field and search for a discount.
After visiting a voucher website, they return and complete their original purchase.
In this case, the publisher receives attribution, but its additional contribution may be limited.
These two scenarios should not automatically be rewarded in the same way.
One of the biggest concerns surrounding voucher publishers is what is sometimes described as checkout interception.
A typical journey looks like this:
The publisher may not have created the original demand.
It may simply have become the final tracked interaction.
However, even this journey does not prove the publisher created zero value. The discount may have prevented abandonment or encouraged a larger order.
That is why customer behaviour and controlled measurement matter.
Cashback affiliates can be incremental when their incentives influence retailer selection, purchasing decisions or customer acquisition.
Cashback works differently from traditional voucher activity.
Instead of providing a promotional code, the publisher generally offers the customer a reward linked to their purchase.
That reward may influence behaviour in several ways.
A customer comparing similar retailers may choose the one offering a more attractive cashback incentive.
A cashback platform may introduce a customer to a brand they have not previously purchased from.
A temporary cashback increase may encourage customers to purchase sooner.
A cashback incentive may influence whether an existing customer returns.
These are potentially valuable outcomes.
However, cashback also creates attribution challenges.
A customer who already intended to buy from a particular retailer may visit a cashback platform purely to collect a reward on their planned purchase.
In that situation, the publisher could receive commission without creating much additional demand.
The important distinction is between influencing a purchase and being present during a purchase.
Both can generate tracked revenue.
Only the first necessarily implies meaningful incremental influence.
Although voucher and cashback publishers are frequently grouped together, their customer propositions and behaviours can differ.
| Area | Voucher affiliates | Cashback affiliates |
|---|---|---|
| Customer incentive | Discount or promotional offer | Reward linked to purchase |
| Common interaction | Searching for deals or codes | Shopping through a rewards platform |
| Potential value | Conversion, retailer selection, acquisition | Retailer selection, acquisition, loyalty |
| Common risk | Checkout interception and code leakage | Commission on already-planned purchases |
| Important measurement | Journey stage, code usage, customer acquisition | New customers, journey stage, reward influence |
| Optimisation opportunities | Exclusive codes, controlled promotions, differentiated CPA | Targeted cashback boosts, acquisition incentives, differentiated CPA |
Neither model is automatically more incremental.
A strong cashback partner could generate considerably more new demand than a weak voucher publisher.
Equally, an exclusive voucher campaign could be more incremental than a cashback partnership predominantly used by existing customers.
The evaluation needs to happen at publisher and campaign level.
Our affiliate publisher types guide explores how these partners fit into the wider ecommerce affiliate ecosystem.
There is no single metric that can definitively prove how much incremental value an affiliate creates.
However, combining several measures can help ecommerce brands make more informed decisions.
Start by measuring the percentage of new customers generated by each publisher.
For example:
| Metric | Publisher A | Publisher B |
|---|---|---|
| Attributed revenue | £50,000 | £50,000 |
| Orders | 1,000 | 1,000 |
| New customer rate | 12% | 48% |
| New customer orders | 120 | 480 |
Both publishers generate identical attributed revenue.
But Publisher B appears to contribute substantially more first-time customers.
If customer acquisition is a strategic objective, that difference matters.
However, new customer acquisition is not the same as incrementality.
A new customer may already have decided to purchase before visiting the affiliate.
An existing customer might make an additional purchase because of the incentive.
New customer percentage is a valuable signal, not definitive proof.
Time-to-conversion analysis helps reveal how customers interact with publishers.
Imagine one voucher partner has a median click-to-sale time of 90 seconds.
Another has a median time of several hours.
The first may be interacting with customers very close to checkout.
That warrants investigation, particularly if the publisher also has a high returning-customer rate.
However, short conversion times do not automatically mean low incrementality.
A customer who discovers a compelling exclusive offer might purchase immediately.
The metric becomes more useful when combined with other information.
Where possible, analyse the interactions preceding an affiliate conversion.
For example:
Journey A: Cashback publisher → Brand website → Product research → Purchase
Journey B: Paid social → Brand website → Email → Checkout → Voucher publisher → Purchase
Journey A suggests the cashback partner may have played a discovery role.
Journey B suggests the voucher publisher entered much later.
Neither journey proves causality on its own.
But repeated patterns can help identify the role each publisher tends to perform.
Where tracking permits, examine:
The aim is to understand the publisher’s contribution rather than simply accept the final attribution result.
Voucher codes can reveal useful information about publisher behaviour.
Questions worth asking include:
Code leakage is particularly important.
Imagine a brand creates an exclusive offer for a creator.
The code is then copied by several voucher websites.
Those websites may begin receiving traffic from consumers searching for the creator’s discount.
The original creator generated the awareness, but another publisher may capture the final affiliate click.
Without proper code controls, reporting can misrepresent which partnership created the demand.
A publisher generating high tracked revenue isn’t necessarily delivering high commercial value.
Returns, discounts, network costs and commission all affect profitability.
Consider this hypothetical example:
| Metric | Publisher A | Publisher B |
|---|---|---|
| Tracked revenue | £100,000 | £100,000 |
| Returned/cancelled revenue | £25,000 | £10,000 |
| Kept revenue | £75,000 | £90,000 |
| Validated commission | £7,500 | £9,000 |
| Commission / kept revenue | 10% | 10% |
The commission rates are identical.
But Publisher B generates £15,000 more retained revenue.
This doesn’t establish that Publisher B is more incremental, but it shows why incrementality should be considered alongside profitability.
A publisher can be incremental and still be commercially unattractive if the margin is insufficient.
Equally, a lower-incrementality partner may still provide a profitable contribution under the right commercial terms.
Affiliate activity rarely operates independently of other marketing channels.
Customers may interact with:
before purchasing.
If a voucher publisher repeatedly appears immediately after branded paid-search interactions, the brand should investigate whether affiliate commission is being paid on demand substantially generated elsewhere.
If a cashback publisher frequently introduces customers before subsequent direct or paid interactions, traditional last-click reporting may understate its influence.
The objective is not to eliminate channel overlap.
It is to understand it and avoid making commercial decisions from incomplete attribution data.
The strongest evidence often comes from testing what happens when affiliate activity changes.
For example, an ecommerce brand could test the impact of:
The key is to measure what happens to total business outcomes, not only attributed affiliate revenue.
If a publisher is paused and affiliate-attributed revenue falls by £50,000, that does not necessarily mean the business lost £50,000 of sales.
Some customers may have purchased through other channels instead.
A well-designed test attempts to estimate that difference.
Tests should account for seasonality, promotional activity, customer mix and other marketing changes. Simply comparing one week with another is rarely sufficient to establish causality.
Consider a hypothetical ecommerce retailer evaluating a major voucher partner.
Before the test, the publisher reports:
The retailer wants to understand whether the partnership is creating additional sales.
It runs a carefully controlled experiment, using a suitable comparison group and measuring total site performance.
The results suggest that removing the publisher reduces total retained revenue by approximately £8,000 over the equivalent measurement period.
If the experiment is valid and the estimate is sufficiently reliable, that would suggest the publisher’s incremental revenue contribution is materially lower than its £40,000 attributed revenue.
An illustrative calculation would be:
Estimated incremental revenue ÷ Attributed revenue × 100
£8,000 ÷ £40,000 × 100 = 20% estimated revenue incrementality ratio.
This is not a universal benchmark or a real Conversion Digital client result.
It illustrates why attributed revenue and incremental revenue can differ.
The next question is whether the additional £8,000 generates enough contribution after discounts, publisher commission, network fees and other relevant costs.
A 20% estimated revenue incrementality ratio is not automatically good or bad.
Commercial value depends on the economics behind it.
Once publisher behaviour is better understood, commission becomes a powerful optimisation tool.
A programme offering every publisher the same CPA may be paying identical rates for very different contributions.
Instead, ecommerce brands can consider differentiated commercial arrangements.
Offer stronger commission for verified first-time customers where acquisition economics support it.
Use an appropriate lower rate where the publisher’s role and customer economics justify it.
Reward partners according to their actual contribution rather than their broad category.
Offer temporary commission increases in exchange for agreed promotional activity.
Reward publishers for achieving meaningful acquisition or incremental-growth objectives.
Apply appropriate rules around code usage, publisher eligibility and approved promotions.
These approaches require reliable tracking and clear programme terms.
For a more detailed explanation, read our guide to affiliate commission rates and structures.
The objective is not simply to pay voucher and cashback publishers less.
It is to ensure commission reflects the value being generated.
Not without understanding the consequences.
Removing voucher publishers can be tempting when an affiliate programme appears overly dependent on discount activity.
But a blanket removal strategy may also eliminate profitable sales and useful promotional partnerships.
Before removing a publisher, ask:
In some cases, the right decision may be to remove the partner.
In others, it may be to renegotiate commission, restrict codes or change the type of activity permitted.
Optimisation should be based on evidence, not a blanket judgement about publisher categories.
The same principle applies.
Cashback can be an effective customer acquisition and conversion channel.
However, if the programme is heavily concentrated around a small number of cashback publishers, the brand may have limited exposure through other parts of the customer journey.
Rather than simply reducing cashback activity, consider whether the programme needs additional investment in:
A healthier strategy may involve diversifying the sources of affiliate revenue while retaining profitable cashback partnerships.
Our guide to growing an affiliate programme explores how recruitment and publisher development can support that diversification.
High concentration isn’t automatically bad, but it may indicate missed opportunities elsewhere.
This can indicate attribution shifts rather than genuine business growth, although other explanations are possible.
This may suggest late-stage interactions worth investigating.
Without this information, evaluating acquisition contribution becomes considerabl
