What is the cost of goods sold (COGS)?

Cost of Goods Sold (COGS), also called Cost of Services for service businesses, represents the direct costs of delivering services to clients. For professional service firms, COGS primarily includes salaries and benefits for billable staff, contractor payments, and direct project expenses (travel, materials, subcontractors). COGS excludes overhead costs like rent, marketing, administrative salaries, and software. A consulting firm paying $180,000 monthly in delivery team salaries and $40,000 in contractor fees has $220,000 in COGS. COGS directly reduces gross profit on the P&L.

Key characteristics of cost of goods sold (COGS)

1. Direct costs only: Expenses tied directly to service delivery

2. Variable or semi-variable: Increases as revenue grows

3. P&L placement: Appears immediately after revenue, before gross profit line

4. Excludes overhead: Rent, marketing, and admin costs are operating expenses, not COGS

5. Service firm COGS: Primarily labor (salaries + contractors), minimal materials

Why the cost of goods sold (COGS) matters for service firms

COGS is the most significant expense for professional service firms, typically 50-65% of revenue. Understanding COGS enables gross margin calculation and pricing decisions. A firm with $500,000 revenue and $325,000 COGS has a 35% gross margin; reducing COGS to $275,000 improves gross margin to 45%, adding $50,000 monthly gross profit. COGS trends reveal cost efficiency: COGS growing faster than revenue indicates margin compression requiring pricing adjustments or delivery optimization. Properly categorizing COGS versus operating expenses is critical: misclassifying overhead as COGS inflates gross margin, creating misleading profitability metrics.

Example: COGS calculation for consulting firm

Monthly COGS breakdown:

1. Billable staff salaries:

2. 5 senior consultants: $70,000

3. 8 consultants: $92,000

4. 3 analysts: $28,000

5. Total salaries: $190,000

Benefits for billable staff:

1. Health insurance: $18,500

2. 401 (k) match: $11,400

3. Total benefits: $29,900

Payroll taxes (billable staff):

1. FICA (7.65%): $14,535

2. FUTA/SUTA: $950

3. Total payroll taxes: $15,485

Contractor payments:

1. 3 contractors for Project Alpha: $28,000

2. 2 specialists for Project Beta: $18,000

3. Total contractors: $46,000

Direct project costs:

1. Client site travel: $4,200

2. Project materials: $1,800

3. Subcontractor services: $2,500

4. Total direct costs: $8,500

5. Total COGS: $290,385

6. Monthly revenue: $485,000

7. Gross profit: $194,615

8. Gross margin: 40.1%

9. NOT included in COGS (these are operating expenses):

10. Administrative salaries: $32,000

11. Rent: $12,000

12. Marketing: $11,500

13. Software: $8,200

14. Insurance (general): $3,800

Analysis:

1. COGS is 59.9% of revenue (reasonable for consulting)

2. Labor costs (salaries + benefits + taxes) are $235,385 (81% of COGS)

3. Contractor costs are $46,000 (16% of COGS)

4. Direct project costs are $8,500 (3% of COGS)