Who this is for
Net margin is where optimistic bookkeeping goes to be found out. The formula is simple subtraction; the discipline is in the operating expense list. Businesses routinely exclude the owner's salary, annual costs that did not bill this month, and software that auto-renews unnoticed, then report a net margin the bank account quietly contradicts.
Enter revenue, direct costs, and complete operating expenses to get gross and net margin together. The completeness checklist below covers the expenses most often missed, because a flattering net margin is worse than a thin honest one: it leads to pricing and spending decisions the real business cannot afford.