If 74% of your revenue comes from existing customers, who is protecting it?

The “Customer Success is a cost centre” argument has a structural flaw. It treats CS as a support function — something that absorbs costs without generating revenue. But this logic only works if you assume that existing customers renew automatically, expand spontaneously, and stay without anyone managing the relationship.

They don’t.

According to the ChurnZero Customer Revenue Leadership Study (2025), 74% of SaaS companies’ revenue comes from existing customers. Not from new logos. Not from marketing campaigns. From the customers already in the system — the ones CS is responsible for.

A cost centre is a function that consumes resources without directly contributing to revenue. By that definition, CS cannot be a cost centre — because it sits directly in the path of the revenue that keeps the company alive.

The confusion arises because CS costs are visible and immediate (salaries, tools, headcount) while CS value is often invisible and diffuse (churn that didn’t happen, renewals that closed without a rescue mission, expansions that came from a relationship rather than a campaign).

This is not a perception problem. It is a measurement problem. And it is fixable.

The first 90 days — where the money actually walks out the door

One of the most underappreciated CS arguments is what happens at the very beginning of the customer lifecycle — before CS is even given credit for “retention.”

The data on early churn is stark:

Consider what this means financially. If a SaaS company spends a median of $702 to acquire a single customer — and then loses that customer within 90 days because no one guided them to value — the entire acquisition investment is gone. Not reduced. Gone.

CS is not the last line of defence at renewal time. It is the first line of value delivery — and the first 90 days are where the economics of the entire customer relationship are determined.

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What public SaaS companies actually spend — and what it tells us

No major SaaS company breaks out “Customer Success” as a separate line item in its financial reporting. CS costs are typically embedded in Cost of Revenue or Sales & Marketing. This invisibility is itself part of the problem — and it is worth naming explicitly.

What we can see, however, is instructive.

Sales & Marketing spend at leading SaaS companies (FY2024, reported 2025)

Company	Total Revenue	S&M Spend	S&M as % Revenue	NRR / Renewal Rate
Salesforce	$34.9B	$12.9B	37%	Not disclosed
ServiceNow	$10.9B	$3.8B	35%	98.5% renewal · 125% NRR
HubSpot	~$2.6B	~$1.2B	46-47%	~102-106% NRR
Private SaaS median (Benchmarkit 2025)	—	—	37-47%	101% NRR median

Sources: Salesforce 10-K FY2024; ServiceNow FY2024 annual report; HubSpot 10-Q FY2024; Benchmarkit 2025 SaaS Performance Metrics Benchmarks (data: 2024, published 2025). Note: Benchmark reports in the SaaS industry are typically published with a one-year data lag. The Benchmarkit 2025 report and High Alpha 2025 Benchmarks Report both confirm these figures as the current industry standard.

These companies collectively spend between 35–47% of total revenue on Sales & Marketing — the function responsible for acquiring new customers. And yet, the most striking number in ServiceNow’s report is not the S&M line. It is the 98.5% renewal rate and 125% NRR. That is the CS function’s contribution — invisible in the P&L, but unmistakable in the unit economics.

The cost of acquiring a new dollar vs. protecting an existing one

Here is the number that should end the “cost centre” conversation — and the one CS leaders should have memorised:

Source: Benchmarkit 2025 SaaS Performance Metrics Benchmarks

Companies now spend $2.00 to acquire every $1.00 of new customer ARR. The same dollar of revenue from an existing customer — through upsell, expansion, or cross-sell — costs half as much. And growing that existing customer requires CS, not Sales.

The Benchmarkit 2025 report adds another critical finding: Expansion ARR now represents 40% of Total New ARR — up 5 percentage points year-over-year. In companies above $50M ARR, this rises to 58–67%. In other words: as companies scale, the majority of their revenue growth comes from existing customers. The function responsible for that growth is CS.

A note on what the data cannot show

No public SaaS company breaks out Customer Success as a separate line item. CS costs are absorbed into Cost of Revenue or Sales & Marketing — making them invisible in standard financial reporting.

This invisibility is the structural reason CS is always at risk of being labelled a cost centre. The costs are on the P&L. The value — in churn that didn’t happen, in expansions that didn’t require a sales cycle, in renewals that closed without a rescue call — is not.

Fixing this is not a financial reporting problem. It is a measurement and communication problem. And it starts with CS leaders knowing their numbers.

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The numbers you need to know before every leadership conversation

The following metrics are not aspirational. They are the minimum financial literacy required to defend CS in any budget conversation, headcount review, or board discussion. Know them. Have them ready. Update them quarterly.

These seven numbers will not eliminate every budget challenge or headcount freeze. But they will change the nature of the conversation — from “justify your existence” to “here is what protecting this revenue base actually costs, and here is what losing it would cost instead.”