Key Principle
Four ratios drawn from the balance sheet and income/expense statement answer four distinct survival questions (Exhibit 2.6, p. 54). Two measure stock (position), two measure flow (performance):
| Ratio | Formula | Threshold | What It Measures |
|---|---|---|---|
| Solvency | Net Worth / Total Assets | >20% | How much asset decline you can absorb before insolvency |
| Liquidity | Liquid Assets / Current Debts | >1.0 (3-6 months of after-tax income in reserves) | Ability to pay bills if income stops |
| Savings | Cash Surplus / After-Tax Income | >5% (avg. American family: 5-8%) | Wealth-building velocity |
| Debt Service | Monthly Loan Payments / Monthly Gross Income | <35% | Income locked into fixed debt obligations |
No universal ideal values exist -- targets depend on personal circumstances, risk tolerance, and economic conditions (p. 55). But breaching these thresholds signals specific vulnerabilities.
Why This Matters
These ratios convert raw financial statement data into diagnostic signals. Without them, a balance sheet and income statement are descriptions, not evaluations. The critical insight is that solvency and liquidity measure different risks: a household can be solvent but illiquid -- positive net worth yet unable to cover next month's bills (p. 55).
The 2008 crisis illustrates the stakes: the S&P 500 fell ~37% and average homes fell ~18% (S&P/Case-Shiller Index, p. 55). A solvency ratio of 20.9% -- like the Cases' -- means a ~21% asset decline triggers insolvency. A crisis of 2008's magnitude would have wiped them out. Meanwhile, their $2,225 in liquid assets covered only 1.5 months of current debts, far short of the recommended 3-6 months of after-tax income ($14,403-$28,806).
Good Examples
Solvency ratio stress test (p. 55): The Cases' 20.9% solvency ratio means they could withstand "only about a 21% decline in the market value of their assets before they would be insolvent." During the 2008 crisis, both stock and housing declines exceeded this threshold. The ratio exposes how thin the margin actually is.
Liquidity vs. solvency independence (pp. 54-55): The Cases have positive net worth ($45,625) but only $2,225 in liquid assets against $17,545 in current debts. They are solvent but dangerously illiquid. If income stopped, they could cover bills for roughly 1.5 months -- well below the 3-6 month minimum.
Savings ratio as wealth-building velocity (p. 55): The Cases' 19.7% savings ratio far exceeds the 5-8% American average, showing strong wealth-building momentum. This ratio is the most direct indicator of whether the surplus-to-net-worth mechanism is functioning.
Counterpoints
"My net worth is positive, so I'm fine." Solvency (long-term survival) and liquidity (short-term survival) are independent conditions. Positive net worth with no liquid reserves means one missed paycheck can trigger a debt spiral even though the balance sheet looks healthy.
"I can always sell assets in an emergency." Illiquid assets (home, retirement accounts) cannot be converted to cash quickly without penalty or loss. The liquidity ratio specifically measures near-cash reserves, not total asset value.
"My debt payments are manageable." A debt service ratio approaching 35% leaves minimal room for variable expenses or savings. Any income disruption -- reduced hours, job loss, medical leave -- immediately creates a deficit with no buffer.
Key Quotes
"Bob and Cathy's solvency ratio is 20.9%, which means that they could withstand only about a 21% decline in the market value of their assets before they would be insolvent." (p. 55)
"Financial plans provide direction to annual budgets, whereas budgets directly affect both your balance sheet and your income and expense statement." (p. 40)
Rules of Thumb
- Solvency ratio above 20%: you can absorb a moderate market correction without insolvency
- Liquidity reserves: 3 months minimum, 6+ months if job security is uncertain or the economy is troubled (p. 55)
- Savings ratio above 5% to build wealth; 10-20% for meaningful progress toward long-term goals
- Debt service below 35% of gross income; lower is better for resilience against income shocks
- Recalculate all four ratios every time you update your balance sheet and income statement (every 3-6 months)
- When two ratios conflict (solvent but illiquid), the weaker ratio identifies the more urgent risk
Related References
- Balance Sheet and Income Statement Construction - how to construct the statements these ratios are computed from
- The Six-Step Financial Planning Process - the planning cycle where these ratios serve as evaluation metrics (step 5)
- Money Psychology and Behavioral Planning - behavioral patterns that cause ratio deterioration