The distinction between cost of goods sold and operating expenses is one of the most consequential classifications in a startup's financial statements. Getting it right determines the accuracy of your gross margin, the comparability of your financials to industry benchmarks, and the credibility of your financial reporting to investors. Getting it wrong — as many early-stage companies do — creates a cascade of distortions that affects almost every financial metric that follows.

The core principle is straightforward: COGS contains costs that are directly associated with delivering your product or service to customers. OpEx contains costs associated with running and growing the business. In practice, the boundary between the two requires judgment — and that judgment has significant financial consequences.

What belongs in COGS

For a software company, COGS typically includes cloud hosting and infrastructure, third-party software and API costs that are directly consumed in delivering the product, customer support costs for product-related issues, and the portion of engineering time spent on maintaining and operating the product rather than developing new features. For a services company, COGS includes the direct labour cost of delivering the service — the salary and associated costs of the people who do the work. For a hardware company, COGS includes raw materials, manufacturing costs, quality assurance, and inbound freight.

The common thread is directness: a cost belongs in COGS if it increases in proportion to your delivery of product or service to customers. If you double your customers and the cost doubles too, it's probably COGS. If it stays approximately constant regardless of customer volume, it's probably OpEx.

The grey areas

Several cost categories sit on the boundary and require a deliberate decision about classification. Customer success is one: the portion of customer success activity that's directly related to onboarding and product delivery belongs in COGS; the portion related to retention and expansion belongs in Sales and Marketing. Implementation and professional services is another: if you provide implementation support as part of the core product offering, those costs belong in COGS; if they're charged separately as an additional service, they belong in their own revenue and cost lines.

The key is to make these classifications explicitly and apply them consistently. The classification itself matters less than the consistency — as long as investors and comparables are using the same methodology, the benchmarking is valid. Inconsistency between periods or between what you report and what peers report is what creates confusion and credibility problems.

Why it matters to investors

Investors benchmark gross margin against industry standards. For SaaS companies, they expect to see 65–80% gross margin. For hardware, 30–50%. For services, 40–65%. If your gross margin is significantly different from these benchmarks — higher or lower — they will ask why. If the answer is that you've classified costs differently from how the benchmark companies classify them, that's a conversation you want to be prepared for. If the answer is that your cost structure is genuinely different and the gross margin reflects that accurately, that's a more interesting conversation about your business model. Either way, knowing the answer — and having a gross margin calculation you can defend in detail — is essential.