Start With Contribution, Not the Headline Discount
Start with the contribution from a delivered one-off order, not the advertised percentage saving. Contribution here means realized sales revenue, excluding GST, less product cost, before advertising, delivery and payment fees. GST in New Zealand is charged at a rate of 15% (Inland Revenue (Te Tari Taake), GST). It is not profit: those other costs still need to be paid (Source: Inland Revenue (Te Tari Taake)).
For illustration only, a $230 GST-inclusive order has $200 of revenue before GST ($230 ÷ 1.15). If the product cost is $120, the one-off contribution is $80, or 40% of pre-GST revenue. A 10% subscribe-and-save discount reduces the customer price to $207, or $180 before GST. Product cost is unchanged, so contribution falls to $60 and the contribution margin to 33.3%. The discount has consumed $20, or one-quarter of the original contribution. ORVX can calculate product cost from a cost model and show gross profit, net profit and margins, then report contribution after advertising by product and collection. Use the pre-discount contribution to decide whether the offer has room before assessing the later subscription effects.
| Measure | One-off order | 10% subscription discount |
|---|---|---|
| Customer price, GST-inclusive | $230 | $207 |
| Revenue before GST | $200 | $180 |
| Product cost | $120 | $120 |
| Contribution | $80 | $60 |
| Contribution margin | 40.0% | 33.3% |
What a Subscription Discount Buys
A subscription discount is buying behaviour, not simply rewarding a customer. The first behaviour is another delivered order: the customer commits to returning instead of deciding from scratch at full price. The second is more predictable demand. Regular orders can make purchasing, stock planning and marketing review more consistent, but that predictability has value only if your own numbers show it reduces a real planning problem.
Use contribution to price that benefit. For illustration only, suppose a one-off order produces $45 contribution after product cost and advertising. A 10% subscription discount on a $100 realised sale reduces revenue by $10, so contribution falls to $35. The discount has purchased the chance of an additional order and a more reliable pattern of demand; it has not automatically purchased either one.
The extra order must be incremental. If the discount raises the probability of an additional delivered order by 40%, and that order would produce $35 contribution, its expected contribution is $14 (0.40 × $35), exceeding the $10 given up. At a 20% increase, it is $7, which does not cover the discount before considering any other benefit. Compare customers’ profitability and repeat behaviour, then check contribution after advertising by product or collection. ORVX reports those measures from delivered orders, so you can distinguish genuinely purchased behaviour from orders that would have happened anyway.
Worked example with sample numbers
This example is illustrative. It uses sample numbers for a motorcycle gear store selling in New Zealand. They are made up to show the method, they are not a benchmark, and your own figures will differ.
Formula: Subscriber margin = orders kept x (margin per order - discount per order).
| Orders kept | One-off order margin | Subscriber margin in total |
|---|---|---|
| 2 | NZ$35.08 | NZ$45.47 |
| 4 | NZ$35.08 | NZ$90.94 |
| 6 | NZ$35.08 | NZ$136.41 |
| 9 | NZ$35.08 | NZ$204.61 |
Run the same sum with your own numbers in the free calculator, or browse guides for sellers in New Zealand and more motorcycle gear guides.
General information only: tax, duty and import rules change and depend on your situation, so check with an accountant or the official source before acting.
Eligible Shopify stores can see these numbers for their own store through the Founding 10,000 offer.
Churn and How Long a Customer Stays
Churn measures customer loss. For a defined period, calculate it as customers who stop renewing during the period divided by customers active at its start. It is the right measure when deciding whether a subscription discount is creating enough commitment to justify lower revenue per order. A rising churn rate can make an apparently attractive price uneconomic before order-level margin shows the problem.
Retained orders measure what remains after the first subscription order: the number of subsequent delivered orders from those customers. This is different from churn. Two subscriptions can have the same churn rate while producing different numbers of delivered orders if renewal timing or order frequency differs. Use retained orders when testing the discount against contribution per order, fulfilment cost and any acquisition cost. The CAC calculator helps isolate the acquisition-cost amount that those orders must recover.
Customer lifetime measures how long a customer remains active, either in time or in delivered orders. Use it for customer lifetime value and payback decisions, rather than as a substitute for current churn or retained orders. A simple expected lifetime of 1 divided by period churn is valid only when churn is stable and the periods are comparable; observed customer histories are more useful when retention changes. ORVX can show customer-level profitability and repeat behaviour, so compare these measures in your own trading currency before changing subscription pricing.
Delivery and Fee Effects
Price each subscription delivery as a new order. Remove GST first: a $115 GST-inclusive payment is $100 of revenue because New Zealand GST is 15% (Inland Revenue (Te Tari Taake), GST). Then subtract the shipping label, pick-and-pack labour, packaging, payment-processing fee, and any platform or subscription-app charge applied per order (Source: Inland Revenue (Te Tari Taake)).
Returns belong in the same calculation as an expected delivery cost. For illustration only, if a $100 ex-GST order carries $9 shipping, $3 fulfilment, $3.20 processing, $1 platform charge and $4 expected return cost, delivery fees consume $20.20. A 20% subscription discount reduces revenue to $80, leaving $59.80 before product cost and advertising. Compare that with the equivalent one-off order using the same cost assumptions, not with the headline price.
Exclude costs that do not change when the subscription is added, such as an existing monthly software plan, warehouse lease or salaried manager. Include a charge only when the subscription creates it or increases it per shipment. ORVX can show realised revenue from delivered orders and report refund value and return rate, helping you replace assumed return cost with your store’s own order history.
How to Read the Worked Example
Read the worked example from left to right. Start with the one-off order’s contribution: this is the baseline available from a customer who buys once. Then compare it with the contribution from each retained subscription order. The relevant change is not the subscription price alone; it is the contribution left after the discount, product cost, delivery effects, fees and any other costs included in the table.
Next, use retained-order value to assess the customer over the period shown. It combines the contribution from the initial order with the contribution from later delivered orders, so it answers whether retention creates more value than the one-off baseline. Payback answers a different question: how long, or how many retained orders, it takes for that accumulated contribution to recover the cost or sacrifice identified in the example. Act on order contribution when an offer’s unit economics are unclear, retained-order value when deciding whether retention is valuable, and payback when setting a tolerable acquisition or incentive cost.
Sources
- GST (goods and services tax) (Inland Revenue (Te Tari Taake), checked 26 October 2026).
How this page was made: drafted with AI from a brief, then checked by automated rules for arithmetic, sources and duplication. The sample numbers were calculated, not reported.