SaaS Finance, Part 2: The P&L Waterfall, Line by Line
A line-by-line explanation of the P&L waterfall for SaaS businesses, with worked examples using two fictional products: CodeVault (a code collaboration platform) and PipelineCI (a CI/CD platform).
Revenue
Total income from selling your product or service. Revenue = Price × Number of Paying Customers, summed across all tiers and products.
CodeVault (code collaboration platform):
Team tier: 200 teams × \$25/user × 8 avg users = \$40,000
Enterprise tier: 15 orgs × \$45/user × 150 avg users = \$101,250
PipelineCI (CI/CD platform):
Pro tier: 80 teams × \$299/month = \$23,920
Total MRR = \$165,170
Total ARR = \$1,982,040
For annual contracts, divide the annual price by 12 to get the MRR contribution.
Cost of Goods Sold (COGS)
Direct costs incurred to deliver your product to customers. COGS answers the question: "What does it cost to serve this customer?"
COGS encompasses several cost types:
| Type | Description | Example |
|---|---|---|
| Per user | Cost for each active user | Cloud compute: $12/user/month |
| Per unit | Cost per unit of consumption | Storage: $0.50/GB |
| Fixed monthly | Flat cost regardless of usage | Data feed: $8,500/month |
| Fixed annual | Annual cost, amortized monthly | Data license: $100,000/year → $8,333/month |
| Percent of revenue | Scales with revenue | Payment processing: 2.9% |
CodeVault COGS:
Cloud compute: 1,600 users × \$3/user = \$4,800
Third-party integrations (Slack, Jira): \$2,500/month
AWS storage: \$3,200/month
Payment processing: 2.9% × \$141,250 = \$4,096
Total COGS: \$14,596
Important distinction:
| Data Acquisition Type | Classification |
|---|---|
| Multi-year subscription serving all customers | COGS - Fixed - Indirect |
| Per-client commercial imagery purchase | COGS - Variable - Direct |
Both are COGS (required to deliver product), but they behave differently with scale.
Gross Profit
Revenue minus COGS. What remains after paying the direct costs of delivering your product.
Revenue: \$165,170
COGS: \$14,596
Gross Profit: \$150,574
Gross Margin: 91.2%
| Range | Assessment |
|---|---|
| Below 60% | Concerning — high delivery costs |
| 60-70% | Acceptable for data/ML-heavy businesses |
| 70-80% | Good — typical mature SaaS |
| 80%+ | Excellent — highly scalable |
Variable Costs
Costs that vary with business activity but aren't directly tied to delivering the product. These scale with revenue or customer acquisition activity.
Variable costs answer the question: "What does it cost to acquire or expand this customer?"
| Type | Description | Example |
|---|---|---|
| Marketing spend | Demand generation budget | Content marketing: $10,000/month |
| Sales commissions | Per-deal compensation | 10% of ACV on new deals |
| Implementation labor | Per-customer onboarding | $15,000 per enterprise customer |
| Partner revenue share | Channel/reseller fees | 15% of contract value |
Enterprise Sales Funnel Costs:
Content marketing spend: \$15,000
SDR salary allocation: \$12,000
Sales commission (5 deals × \$18,000 ACV × 10%): \$9,000
Implementation (5 customers × \$12,000): \$60,000
Total Variable: \$96,000
The distinction between COGS and Variable Costs matters: COGS measures efficiency of delivery (affects Gross Margin), while Variable Costs measure efficiency of acquisition (affects Contribution Margin).
Contribution Profit
Gross profit minus variable costs. What each customer "contributes" after accounting for the cost to acquire and serve them.
Gross Profit: \$150,574
Variable Costs: \$96,000
Contribution Profit: \$54,574
Contribution Margin: 33.0%
Contribution margin tells you if your unit economics work. If contribution margin is negative long-term, you lose money on every customer.
In early months with high implementation costs, contribution margin may be negative. This is acceptable if implementation is one-time, steady-state contribution is positive, and LTV:CAC is healthy (3:1+).
Operating Expenses (OPEX)
Fixed costs required to run the business, regardless of customer count. OPEX answers: "What does it cost to maintain the business regardless of how many customers we have?"
Shared Costs
| Category | Examples | Typical Range |
|---|---|---|
| Infrastructure | Cloud hosting, database, CDN | $200-5,000/month |
| Engineering Tools | GitHub, AI tools, IDEs | $100-1,000/month |
| Operations | Auth provider, analytics, email | $100-500/month |
| Compliance | SOC2, legal, insurance | $10,000-50,000/year |
Staffing (OPEX portion)
| Function | P&L Line | Example |
|---|---|---|
| Engineering | R&D | $18,000/month loaded |
| Product | R&D | $15,000/month loaded |
| Executive | G&A | $25,000/month loaded |
| Operations | G&A | $12,000/month loaded |
Shared Costs:
Cloud hosting: \$500
Database: \$200
GitHub: \$200
Auth provider: \$29
Subtotal: \$929
Staffing (OPEX):
Engineering: \$36,000
Product: \$15,000
Executive: \$25,000
G&A: \$8,000
Subtotal: \$84,000
Total OPEX: \$84,929
EBIT (Earnings Before Interest & Taxes)
Operating income. What remains after all operating costs. Also called "Operating Profit."
Contribution Profit: \$54,574
OPEX: \$120,000
EBIT: -\$65,426
EBIT Margin: -39.6% (growth stage, investing ahead of revenue)
Early-stage startups often have deeply negative EBIT. This is expected when investing in growth before revenue scales. Check unit economics (contribution margin trend) to assess if the path to profitability is viable.
Depreciation & Amortization (D&A)
- Depreciation: Non-cash expense allocating cost of physical assets over useful life
- Amortization: Non-cash expense allocating cost of intangible assets over useful life
For asset-light SaaS, D&A is typically small — estimate at 1-3% of revenue unless you have specific data.
D&A is already subtracted in arriving at EBIT (it's part of OPEX). To get EBITDA, you add it back.
For cloud-native businesses, D&A is small because infrastructure is rented (AWS, GCP), not owned, there are no factories or heavy equipment, and intangibles are minimal unless M&A has occurred.
Revenue: \$165,170
Estimated D&A (2%): \$3,303
EBITDA
Earnings Before Interest, Taxes, Depreciation, and Amortization. A proxy for operating cash flow.
EBITDA is greater than or equal to EBIT because you're adding back the non-cash D&A expenses.
EBIT: -\$65,426
D&A: \$3,303
EBITDA: -\$62,123
Why PE investors focus on EBITDA: it's the valuation standard (deals priced using EV/EBITDA multiples), it indicates leverage capacity (lenders use Debt/EBITDA ratios), and it enables comparability (strips out D&A, interest, taxes for cross-company comparison).
For asset-light SaaS, EBITDA ≈ EBIT since D&A is small.
Interest & Taxes
- Interest: Cost of debt financing (loans, credit lines)
- Taxes: Corporate income taxes
For early-stage modeling, focus on EBIT/EBITDA. Interest and taxes are typically added later for board/investor reporting.
Net Income
The bottom line. Profit remaining after all costs, interest, and taxes.
Early-stage startups often have negative net income. This is expected when investing in growth.
Complete Example
REVENUE
CodeVault: \$141,250
PipelineCI: \$23,920
Total Revenue: \$165,170
COST OF GOODS SOLD
Cloud compute: \$4,800
Third-party integrations: \$2,500
Storage: \$3,200
Payment processing: \$4,096
Total COGS: \$14,596
GROSS PROFIT: \$150,574 (91.2%)
VARIABLE COSTS
Marketing spend: \$15,000
SDR allocation: \$12,000
Sales commissions: \$9,000
Implementation: \$60,000
Total Variable: \$96,000
CONTRIBUTION PROFIT: \$54,574 (33.0%)
OPERATING EXPENSES
Shared Costs: \$5,000
R&D Staffing: \$75,000
G&A Staffing: \$40,000
Total OPEX: \$120,000
EBIT: -\$65,426 (-39.6%)
+ D&A: \$3,303
EBITDA: -\$62,123 (-37.6%)
This example shows a growth-stage month where the company is investing in R&D and sales ahead of revenue. As the customer base grows and implementation costs normalize as a percentage of revenue, contribution margin expands.