Formula
Business profit = max(0, gross income − deductible expenses)
Reserve = max(0, profit × income tax rate + profit × self-employment rate − credits/payments)
What the result means
The reserve is cash to hold back under the entered assumptions. It does not account for brackets, deductions outside the business, special tax-base adjustments, local taxes, or filing status.
Tax rules and rates change and depend on jurisdiction. This is an estimate, not tax advice; verify current rules or consult a qualified professional.