Principle
An attach rate measures how often two products are sold together. It does not measure whether the second product was sold, wanted, used, or renewed. In organisations where the second product is bundled, discounted to near zero, or included to close the first, the attach rate is measuring the sales team's negotiating tactics rather than the company's multi-product position.
Behaviour
A company with a second product wants evidence that its customers adopt it. The metric selected is attach rate, and the sales organisation is compensated on it. Reps respond by attaching the second product to deals, which is what they have been asked to do, and the most efficient way to attach a product a customer did not ask for is to make it cost approximately nothing.
The second product now appears in a majority of contracts. Attach rate is reported as strong evidence of a platform strategy taking hold. What has actually happened is that a product with a nominal list price is being given away as a closing concession on the first product, and its presence in the contract carries no information about whether the customer values it.
The mechanism becomes visible only in the usage data and the renewal. The attached product shows minimal activation. At renewal the customer, who never wanted it, declines to pay for it at anything approaching list, and the organisation discovers that the platform revenue it has been reporting was a discount on the core product wearing a different name.
The attach rate is measuring the sales team's negotiating tactics rather than the company's multi-product position.
Evidence
Calculate the effective realised price of the attached product, net of the discount applied to the bundle relative to standalone pricing of the primary product. Where the implied price of the second product approaches zero, it has not been sold.
Examine activation and usage for the attached product across the customer base, segmented by whether it was purchased standalone or attached. Attached products with materially lower activation rates were not wanted, and their contribution to reported ARR is unlikely to survive a renewal in which they are separately priced.
Test renewal behaviour directly. Where any cohort of customers has been required to renew the second product at standalone pricing, their retention rate for that product is the only honest measure of demand available in the business, and it is frequently a fraction of the attach rate that management reports.
Psychology
Nobody in the chain is behaving improperly. The rep is compensated on attach and attaches. The product leader wants adoption and celebrates the attach number. The CRO reports a platform narrative to the board that the attach rate genuinely supports, and the board hears evidence of a strategy working.
The mechanism survives because no single party sees the whole picture. The rep does not track activation. The product team does not see the discount structure. Finance sees a bundled contract value and allocates revenue by list price, which is precisely the number the discount was designed to obscure. Each function's data is accurate and the composite is misleading.
Commercial Risk
A multi-product narrative supports a valuation multiple in a way a single-product narrative does not. Where the second product's ARR is an accounting allocation of a discount on the first, the multiple is being paid on revenue that does not have the characteristics multi-product revenue is assumed to have: it is not independently retained, it does not expand, and it will not survive being separately priced.
The risk crystallises at the first renewal where the acquirer, seeking margin, attempts to charge for the attached product at anything approaching its list value. The customer declines, the ARR restates, and what appeared to be a churn event in the second product is in fact the recognition of a discount that had been capitalised into the acquisition price.
Investment Committee Note