Claim
The traditional formula (Sales − Expenses = Profit) is mathematically correct but behaviorally backwards. Demand for resources expands to fill supply; if all revenue flows into one operating account, expenses always expand to consume it, leaving profit as an afterthought. Inversion: Sales − Profit = Expenses. Take profit out first into a separate account; the business is forced to operate on what remains.
Mechanism
Five-step implementation: (1) read the book — system requires understanding the principles. (2) Determine target percentages by revenue tier ($0-250K: 5% profit / 50% owner / 15% tax / 30% opex; $1-5M: 10-15% profit / 35% owner / 15% tax / 40% opex). (3) Open five separate bank accounts (Income, Profit, Owner's Pay, Tax, OpEx) — physical separation is the behavioral mechanism. (4) Twice-monthly allocation rhythm (10th + 25th): transfer target percentages from Income to dedicated accounts. (5) Quarterly review and adjust 1-3 percentage points toward target — gradual, not overnight.
Conditions
Holds when:
- The business has cash discipline to actually leave the profit account untouched.
- Banking allows multiple accounts cheaply (US small-business banks, mostly).
Fails when:
- Hyper-growth startups deliberately running negative margins to capture market.
- Businesses with highly seasonal cash flow where rigid percentages strain liquidity.
Evidence
"The traditional accounting formula (Sales − Expenses = Profit) is mathematically correct but behaviorally backwards; flipping it to Sales − Profit = Expenses forces the business to live within its means."
"Demand for a resource expands to consume the supply available." (C. Northcote Parkinson, applied)
— Mike Michalowicz, Profit First (synthesized from operator's published work)
Signals
- Business has 5 named bank accounts with target percentages documented.
- Allocation transfers happen on schedule, not when the operator remembers.
- Quarterly review tracks actual vs. target percentages and adjusts 1-3 points.
Counter-evidence
VC-backed growth-stage SaaS deliberately runs negative profit to capture market — Profit First would force premature optimization. Some accountants argue the system creates false comfort by hiding cash crunches inside a profit account that has to be tapped.
Cross-references
- (none in current corpus)