Use case
How to see margin after AI cost, per customer
Revenue per customer is in your billing system. AI cost per customer is in your provider invoice. Margin lives in neither, until you connect them.
Attribute every proxied call with x-customer-id so AI cost accumulates per customer, then load that customer's revenue into Spendline. Margin is revenue minus attributed AI cost, computed continuously rather than reconstructed at quarter-end.
How Spendline does this
The attribution half is the same mechanism as tracking cost per customer: a header on every call, written to an append-only ledger. The margin half is revenue you already have in your billing or CRM system, loaded against the same customer ID. Once both sides exist, margin is a live number, not a spreadsheet someone rebuilds when the board asks.
Why it matters
For an AI-native SaaS company, a customer that looks profitable on subscription revenue alone can be losing money once AI cost is netted out, usually the heaviest users of the product, which is the opposite of what a revenue-only view shows. That inversion is invisible until cost is attributed at the same granularity as revenue.
Frequently asked questions
Do I need to migrate my billing system to Spendline?
No. Spendline attributes and records AI cost; it reads customer revenue rather than replacing wherever you already manage billing.
How current is the margin number?
As current as the last proxied call. Cost accumulates in real time as calls are made; margin reflects that immediately rather than on a reporting cadence.
See where this stands in your own setup
This page describes the mechanism. The 5 minute assessment scores your own attribution, enforcement, and reconciliation setup, so you know exactly which of these problems you actually have today.
Run the 5 minute assessment