I often get asked by founders: “How much can we afford to give away in a welcome bonus when our average order value (AOV) is £50?” It’s a pragmatic question — one that sits at the intersection of psychology, unit economics and growth testing. I’ll walk through a simple framework I use with SMEs to pick a welcome offer that drives acquisition and trial without eroding margins or training customers to expect freebies.
Start with the math: what you can actually afford
Before you think about percentages or messaging, you need to translate your business economics into a per-customer number. The clearest place to start is with contribution margin per order and expected customer lifetime value (CLTV).
Here are the core inputs I use (you’ll want your own numbers, but I’ll use example figures so you can follow the logic):
From that, a simple CLTV (revenue-based) looks like this:
| Annual revenue per customer | £50 × 2 = £100 |
| Lifetime revenue (2 years) | £200 |
| Contribution margin per order | £20 |
| Annual contribution margin | £20 × 2 = £40 |
| Lifetime contribution margin | £40 × 2 = £80 |
So, in this simplified model your average new customer generates about £80 contribution margin over their lifetime. That £80 is the pot you can use to justify acquisition spend and welcome incentives combined.
How much of that pot should be the welcome bonus?
There’s no universal answer—different businesses prioritise growth versus immediate margin—but I use a rule of thumb: allocate no more than 20–30% of CLTV to marketing-driven one-time incentives (welcome bonus + acquisition CAC). That means, of the £80 CLTV, aim to keep total welcome bonus + any extra cost-to-acquire below about £16–£24.
If you’re aiming to be conservative and keep margin healthy, start around 10–15% of CLTV for the welcome bonus itself. For our example that’s roughly £8–£12.
Translating that to a usable customer-facing offer
Customers think in percentages and round numbers. Common welcome formats:
Using our example, a £10 off welcome voucher on a £50 AOV equals a 20% discount. That sits in the sweet spot psychologically (customers love round percent offers) and fits the budget I recommended (≈12.5% of CLTV). But whether you can afford £10 depends on:
Model different redemption scenarios
It’s useful to model several redemption rates. Below I show three scenarios with a £10 welcome credit and our base economics:
| Metric | Low redemption (15%) | Mid redemption (30%) | High redemption (45%) |
|---|---|---|---|
| Per-redemption cost | £10 | £10 | £10 |
| Expected cost per acquired customer | £1.50 | £3.00 | £4.50 |
| CLTV (£) | £80 | ||
| Cost as % of CLTV | 1.9% | 3.8% | 5.6% |
Those numbers show a welcome credit is affordable even with a high redemption rate—because most customers won’t redeem in the first transaction if you structure the voucher right (see mechanics below). If you offered a 20% discount (that's £10 on a £50 AOV) on the first purchase and everyone redeemed, the cost would be much higher relative to margins (but still likely workable if margins are healthy).
Design mechanics to protect margin
How you structure the welcome offer has a big impact on realised cost:
Consider behavioural effects
Welcome offers are not just costs — they’re signals that shape customer behaviour:
So you need to balance short-term conversion lift against long-term margin risk. My preference for many SMEs is a modest immediate incentive plus a second-purchase nudge. That combination turns a one-off discount into a retention lever.
Practical quick tests to run this month
Track these KPIs: sign-up conversion rate, voucher redemption rate, incremental AOV, customer acquisition cost (CAC), and cohort CLTV after 90 and 180 days.
Rules of thumb I use with clients
If you want, I can sketch the same model with your specific margins, repeat rates and current CAC. That’s the only way to give a truly precise recommendation — but the framework above will let you start safely and test toward the right welcome offer for your business.
