COGS Variables

This article explains COGS (Cost of Goods Sold) variables in Model Reef.

You will learn:

• What a COGS variable represents.

• How COGS variables are typically driven by revenue or units.

• How COGS affects P&L, working capital and cash.

• Patterns for modelling unit cost, margin and inventory like behaviour.

1

What a COGS variable is

A COGS variable represents the direct cost of delivering revenue, for example:

• Cost of materials or goods sold.

• Direct labour that can be directly tied to production.

• Payment processing fees tied to revenue.

• Hosting costs closely linked to user activity.

Each COGS variable:

• Lives in a branch alongside its related revenue where possible.

• Has a category such as COGS - Direct or COGS - Platform.

• May use units, revenue or both as its basis.

2

How COGS variables use drivers

COGS variables are often tied tightly to revenue or units via drivers, for example:

• Unit cost pattern

  • COGS = Units * UnitCostDriver.

  • UnitCostDriver may itself change over time based on scale or inflation.

• Margin based pattern

  • COGS = Revenue * COGSPercentDriver.

  • Or equivalently Gross Margin = Revenue * MarginPercentDriver.

• Hybrid patterns

  • A fixed cost component plus a variable cost per unit.

  • Separate COGS variables for different product lines or channels.

Operational drivers supply units or activity levels. Economic or modifier drivers supply unit cost or percentage patterns.

3

COGS in the P&L

In the P&L:

• COGS variables reduce Gross Profit.

• Categories and subcategories let you see COGS by product, channel or function.

• Gross Profit and Gross Margin are calculated from the combination of revenue and COGS variables.

This creates a transparent link between unit economics and headline margins.

4

COGS, working capital and Accounts Payable

In the Balance Sheet:

• If COGS is paid in the same period as incurred, there is no payable.

• If there is a delay (for example supplier terms of 30 or 60 days):

  • COGS is accrued in P&L when the cost is incurred.

  • An Accounts Payable balance is created to reflect the unpaid amount.

  • Accounts Payable decreases when cash is paid.

Although Model Reef does not model inventory as a separate stock account by default, delayed COGS combined with payables can approximate many inventory timing patterns.

5

COGS in the Cashflow Statement and Cash Waterfall

In the Cashflow Statement:

• COGS variables feed into Payments to suppliers as cash outflows.

• Timing reflects payment terms rather than accrual timing.

In the Cash Waterfall:

• COGS is shown as a line directly under revenue, matching the P&L.

• Changes in working capital then adjust for timing differences before capex, debt and equity flows.

This makes it easy to see both accrual margin and cash impact in one view.

6

Common COGS modelling patterns

Examples:

• SaaS or software

  • COGS driven by user count or traffic, for example hosting and support.

  • Margin drivers showing COGS as a percentage of revenue.

• Retail and ecommerce

  • Unit cost driven COGS with volume discounts.

  • Supplier payment terms representing trade credit.

• Manufacturing

  • Material and direct labour cost per unit.

  • Capacity driven costs related to machine hours or production runs.

Each pattern uses COGS variables to encode the direct economic cost of delivering revenue.

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