Unit economics and finance
The P&L for startups
Reading and building an income statement — revenue recognition, COGS, S&M / R&D / G&A, EBITDA and net income — with a worked $5M ARR SaaS example.
The P&L (profit and loss statement), also called the income statement, answers: over this period, what did we earn, what did it cost to deliver, what did we spend to operate, and what was left? It is not the same as cash in the bank — that is the cash flow statement — but it is the map of the economic engine.
Founders live in bank balances. Investors and boards live in both. Engineers who can read a P&L understand why "we're hiring" and "we're freezing headcount" happen when they do.
Concepts in this section
Read them in order.
| Step | Concept | What it answers |
|---|---|---|
| 1 | Income statement lines | What is revenue, COGS, S&M, R&D, G&A? |
| 2 | Revenue recognition | Why isn't the Stripe dashboard "revenue"? |
| 3 | EBITDA and net income | Which profit number is someone quoting? |
| 4 | A $5M ARR P&L | What does a growth SaaS statement actually look like? |
A $5M ending-ARR SaaS that grew all year might recognize $4.2M of revenue, take 78% gross margin, spend $3.2M on S&M, $2.0M on R&D, $0.9M on G&A, and post about −$2.9M operating income. That can be on plan. The same company might burn only ~$2.1M of cash if customers prepaid — deferred revenue is a SaaS gift when they do, AR is a tax when they do not.
Headcount dominates. A fully loaded US-hub engineer is roughly $200–280k all-in as of 2025–2026. "We only hired two people" is about $500k/year. A 12-person eng org at $22k fully loaded each is already ~$3.2M/year. When headcount freezes hit R&D while S&M keeps hiring, someone has decided growth efficiency matters more than feature velocity this half. Ask which metrics (magic number, burn multiple, GM) drove the call.
At seed, $200k revenue against $1.5M of R&D-heavy opex is normal if the goal is product learning. At Series B, S&M is often the largest opex line and operating income is still deeply negative if growth is the mandate. Public-scale reading lives in reading company financials and the Rule of 40. If you lead a team, know your monthly run-rate as a fraction of company opex. Score infra COGS cuts next to ARR shipped — leaders who only score ARR systematically under-invest in margin.
Common mistakes
- Treating Stripe cash as revenue in investor updates.
- Moving COGS into R&D to inflate gross margin for a fundraise.
- Booking one-time services as recurring without calling it out.
- Managing the company off only the P&L or only the bank. They diverge on purpose.
Key takeaways
- The P&L flows Revenue → Gross profit → Operating income → Net income.
- Subscription revenue ≠ cash collected; ASC 606 spreads it over the service period.
- Opex is mostly S&M, R&D, G&A; headcount dominates all three.
- A $5M ARR growth SaaS can show ~$4M revenue, healthy ~78% GM, and a multi-million operating loss while still being on plan.
- Always pair the P&L with cash / burn.
Further learning
Sal Khan’s intro to the income statement:
EBITDA explained in the same series:
Aswath Damodaran (NYU) resourcesDamodaran Online: Home Page for Aswath Damodaranpages.stern.nyu.eduRelated
Cash flow and the three statements
Why profit ≠ cash, how the balance sheet and cash flow statement work, deferred revenue from annual prepay, and how the three statements link.
Burn, runway and default alive
Calculating burn and runway, the default-alive test, and how to extend runway.
Reading company financials
How to read a 10-K or S-1 so you can judge an employer, a customer, or a competitor — not so you can become an analyst.