Why marketing and finance report different customer acquisition costs

The disagreement may be about definitions

Marketing divides advertising spend by new customers attributed to paid campaigns. Finance includes salaries, agencies, tools and sales effort. The resulting figures differ because the teams are measuring different things.

Both can be useful if labelled accurately. Neither is useful when presented as the single acquisition cost without a definition.

My Day 7 post highlights the cost, denominator and timing differences behind this recurring argument. Start by reconciling the calculation before debating performance.

Define the cost boundary

List the costs included in the numerator. A media-only figure can help monitor an advertising account, but it excludes creative, staff and other work needed to acquire customers.

A channel view should explain which production, tools, agency and personnel costs are allocated to that channel. A fully loaded view should define the relevant sales and marketing costs and how shared resources are treated.

There is no value in making the definition artificially complex. Use a consistent allocation method appropriate to the decision and show the limitations.

Define the customer count

Count new customers according to a clear rule. Do not mix leads, trials, orders and customers. Repeat purchases are revenue from existing customers rather than newly acquired customers.

For a channel-specific calculation, explain how attribution assigns the customer. For a blended business view, include the acquisition sources covered by the cost base.

Avoid dividing paid-media costs by every new customer and then describing the result as the cost of paid acquisition. That mixes a narrow numerator with a broader denominator.

Align the timing

If a buying cycle spans months, this month's spending may not have produced this month's customers. Review cohorts or use a clearly explained lag where the data supports it.

For an early company, the sample may be too small for a stable figure. Report the observed calculation while resisting the temptation to treat it as a permanent benchmark.

Stripe's CAC guide provides additional context on acquisition-cost calculation. Use external guidance to clarify the method, then keep the company's own definitions explicit.

A hypothetical reconciliation

Suppose a team spends $6,000 on media and records 20 new customers attributed to that activity. The media-only cost per attributed customer is $300.

If the relevant acquisition work also includes $4,000 of other costs, the same customer group implies $500 per customer under that wider cost boundary. Neither figure tells the whole company's CAC unless the scope matches the whole acquisition system.

The numbers are illustrative. The lesson is to show what each calculation includes rather than letting a favourable label hide the difference.

Compare cost with the value that can support it

Revenue alone does not show how much is available to recover acquisition spending. Consider gross profit or a clearly defined contribution measure, retention and the timing of receipts and costs.

Projected lifetime value can be highly uncertain for a young business. Show assumptions and use observed customer behaviour wherever possible. A confident ratio based on speculative retention can create false comfort.

Agree the reporting standard

Publish the definitions with the dashboard and use the same terms in budget meetings. Keep narrower operational metrics alongside the broader business view so teams can improve execution without losing sight of the economics.

First 10's analytics work is intended to make these measures usable for decisions, including when the honest answer is that the current data is not yet strong enough to justify scaling.

Apply this to your business

Calculate CAC twice using the same period: once from ad spend alone and once from all acquisition effort. Explain the difference before comparing channels.