Your 72% gross margin was mostly fixed cost
Gross margin held at 72% for three years. Then diligence recomputed it at 58%. The costs in the COGS line had quietly stopped being variable.
Priya's board loved one number. In her company, gross margin held at 72% for three years running, steady enough that the deck stopped explaining it. Then the Series C lead reran the math in diligence and found 58%.
The gap wasn't fraud. It was classification. The COGS line carried a slice of the engineering team, most of customer success, and a share of data-platform cost. None of it moved when the company added a customer. GAAP lets you park those costs in cost of goods sold, and the parking flattered the margin while hiding what the business did per unit.
SaaS companies get wide latitude here. Classify the CS team as COGS and you report a lower margin with honest operating leverage. Classify the same team as operating expense and you report a prettier margin that buries a fixed cost. Both pass an audit. Investors read straight through to the economics underneath.
The number that matters is the marginal one. Add one more customer: what new cost shows up? At most SaaS companies the answer is hosting, third-party usage, payment processing, and a thin layer of support. The engineers who build the product don't scale with the customer count. The CS manager carrying fifty accounts doesn't either, right up until account fifty-one forces a new hire. Most of what sits in COGS is fixed at the horizon that counts.
Operating leverage is why this bites. A company with a real 72% margin scales differently than one running a real 58% with ten points of fixed cost mislabeled as variable. Say growth stalls or the raise slips: the second company discovers expense it assumed was elastic and isn't. The unit economics nobody reopens is where this hides.
The bill rarely lands on the P&L. It lands at the term sheet, when the lead reprices the number with a tighter definition and the valuation comes in well under what the founder pitched. The founder explains the classification. The lead keeps their number. The round closes lower, or it doesn't close.
So carry both. Report the GAAP margin in the statements. Track the marginal margin on the operating dashboard, and run the company against that one. Bring both to the fundraise with a plain account of the difference. The founder who's already done that arithmetic walks in with the one thing diligence can't manufacture: a number that survives being recomputed.