# The operating model: three statements, linked

> Northwind's fourth quarter as three linked statements: drivers in, cash derived, and a balance sheet that balances without a plug.

Source: https://lopifi.com/learn/three-statement-operating-model
Part of: Lopifi — US GAAP books on autopilot, checked by a CPA (https://lopifi.com)

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**How do I build a three-statement financial model for a startup?** Northwind's fourth quarter as three linked statements: drivers in, cash derived, and a balance sheet that balances without a plug.

A P&L forecast says whether the company will make money. It can't say whether the company will have money, because profit and cash differ by working capital and by spending that isn't expense. An [operating model](https://lopifi.com/md/glossary/operating-model) forecasts all three statements, linked. Profit flows into [retained earnings](https://lopifi.com/md/glossary/retained-earnings), balances like receivables come from [drivers](https://lopifi.com/md/glossary/driver), and cash is derived from the [cash flow statement](https://lopifi.com/md/glossary/cash-flow-statement). It's never typed. If the links are right, the balance sheet balances every month without a plug.

*[Figure: three statements]*

Illustrative: one period's revenue and expenses, landing on all three statements at once.

Drivers (Growth, margins, costs, days.) → P&L (Revenue less costs.) → Working capital (Receivables, stock, payables from days.) → Cash flow (Net income plus the changes, by the indirect method.) → Balance sheet (Opening cash plus the cash flow. Assets equal liabilities plus equity.)

One month of the model, in the order it's computed.

## Northwind's Q4 drivers

| Driver | Value | From |
| --- | --- | --- |
| Revenue growth, a month | 5% | Assumption |
| Cost of revenue ÷ revenue | 54.0% | September actual |
| Payroll, its tax, rent and power, a month | 11,492.60 | September actual |
| Receivable days | 21.0 | Trade share of sales (70%) on 30-day terms |
| Payable days | 30 | Supplier's 30-day terms |
| Inventory days | 1.8 | September actual |
| Deferred revenue earned in October | 3,000 | The September deposit, delivered |

The base case. Actuals are read off September; the rest are the founders' assumptions.

*[Balance sheet]*

The opening balance sheet: Northwind at September 30, 2026. USD.

|  | October | November | December |
| --- | --- | --- | --- |
| Revenue | 33,075 | 34,728.75 | 36,465.19 |
| Cost of revenue | (17,850) | (18,742.50) | (19,679.63) |
| Operating expenses | (12,592.60) | (12,592.60) | (12,592.60) |
| Net income | 2,632.40 | 3,393.65 | 4,192.96 |
| Add back depreciation | 500 | 500 | 500 |
| Change in receivables | (14,514.84) | (1,900.16) | (391.21) |
| Change in inventory | (16.13) | (86.37) | (17.78) |
| Change in prepaid insurance | 600 | 600 | 600 |
| Change in payables | 11,289.80 | 1,539.07 | 233.14 |
| Change in other liabilities | (3,000) | 0 | 0 |
| Operating cash flow | (2,508.77) | 4,046.19 | 5,117.11 |
| Financing: dividend paid | (500) | 0 | 0 |
| Closing cash | 32,343.83 | 36,390.02 | 41,507.13 |
| Total assets | 84,714.80 | 89,647.52 | 94,073.62 |
| Total liabilities and equity | 84,714.80 | 89,647.52 | 94,073.62 |
| Difference | 0 | 0 | 0 |

Q4, three statements linked. Projections, not actuals.

Read October. Net income is 2,632.40 and operating cash flow is (2,508.77). The gap is working capital you can name. Receivables grow because the trade invoice is now a full month outstanding ((14,514.84)). The deposit Northwind banked in September is earned in October with no cash moving ((3,000)). The supplier, on 30-day terms, funds part of it (11,289.80). By December the pattern settles, and operating cash flow is 5,117.11 on net income of 4,192.96.

> “For example, major classes of deferrals of past operating cash receipts and payments and accruals of expected future operating cash receipts and payments, including, at a minimum, changes during the period in receivables pertaining to operating activities, in inventory, and in payables pertaining to operating activities, shall be separately reported.”

© Financial Accounting Foundation. All rights reserved.

— [ASC 230-10-45-28, -45-29](https://asc.fasb.org/230/tableOfContent), The indirect method, and what it must separately report

> **Cash is the last line computed, never the first typed. If the balance sheet needs a plug to balance, the model is wrong somewhere upstream.**

**Wrong:** Closing cash = opening cash + net income
October: 35,352.60 → 37,985

**Right:** Closing cash = opening cash + operating, investing and financing cash flow
October: 35,352.60 → 32,343.83

The shortcut assumes every sale is collected and every cost paid in the same month. Northwind's October proves it wrong by thousands of dollars.

**Driver-based, three statements linked**
- Pro: Change one assumption and every line moves
- Pro: Balances by construction, so errors show
- Con: Takes longer to set up
- Con: Every driver has to be defensible
- Best for: Any forecast someone will make decisions from

**Line-by-line, P&L only**
- Pro: Fast
- Con: Cash doesn't tie to anything
- Con: Every change means retyping cells, and they drift
- Best for: A first rough cut, never a board pack

Two ways to build the forecast.

**Use case — What longer payment terms cost.** Change one driver. Put the trade customer on 60-day terms and receivable days double: profit doesn't move, but October's cash does, by roughly another month of the trade invoice. That's the model's value. A pricing, hiring or terms decision shows up in cash, not just in profit.

## Where this lesson's rules come from

- [ASC 230-10-45-28, -45-29](https://asc.fasb.org/230/tableOfContent) — The indirect method, and what it must separately report (codification)
- [Wikipedia, “Financial modeling”](https://en.wikipedia.org/wiki/Financial_modeling) — Financial modeling — background (reference)

## Read further

- https://lopifi.com/md/journal-entries/deferred-revenue
- https://lopifi.com/md/journal-entries/customer-deposit
- https://lopifi.com/md/journal-entries/sale-on-account
- https://lopifi.com/md/journal-entries/inventory-purchase
- https://lopifi.com/md/calculators/working-capital
- https://lopifi.com/md/calculators/dso
- https://lopifi.com/md/calculators/dpo
- https://lopifi.com/md/calculators/free-cash-flow
- https://lopifi.com/md/differences/balance-sheet-vs-income-statement
- https://lopifi.com/md/differences/retained-earnings-vs-net-income
- https://lopifi.com/md/differences/direct-vs-indirect-method
- https://lopifi.com/md/startups/cash-flow-statement-explained
- https://lopifi.com/md/startups/balance-sheet-explained
- https://lopifi.com/md/startups/how-to-read-an-income-statement
- https://lopifi.com/md/accounting/cash-flow
- https://lopifi.com/md/accounting/balance-sheet
- https://lopifi.com/md/accounting/p-and-l
- https://lopifi.com/md/accounting/deferred-revenue
- https://lopifi.com/md/docs/domain/03-statement-semantics
- https://lopifi.com/md/docs/catalog/13-metrics-and-analysis

- **Track:** [Finance](https://lopifi.com/md/learn/finance)
- **Lesson:** Lesson 5 of 8 — 13 min
- **Terms taught:** [Operating model](https://lopifi.com/md/glossary/operating-model), [Driver](https://lopifi.com/md/glossary/driver), [Forecast](https://lopifi.com/md/glossary/forecast), [Cash flow statement](https://lopifi.com/md/glossary/cash-flow-statement), [Retained earnings](https://lopifi.com/md/glossary/retained-earnings), [Working capital](https://lopifi.com/md/glossary/working-capital), [Indirect method](https://lopifi.com/md/glossary/indirect-method), [Deferred revenue](https://lopifi.com/md/glossary/deferred-revenue)
- **Previous:** [The flexed budget, Finance · Lesson 4](https://lopifi.com/md/learn/budget-vs-actual-variance-analysis/flexed-budget)
- **Next:** [SaaS metrics and unit economics, Finance · Lesson 6](https://lopifi.com/md/learn/saas-metrics-and-unit-economics)
- **The course:** https://lopifi.com/md/learn