Estimating Retirement Needs
Retirement marks the phase in your life when your income is derived from financial capital, not human capital. One number drives every other retirement decision, and it takes two lines to compute:
Annual Income Need = Annual Expenses Other Income (Social Security, pensions, rents)
The portfolio only has to fund the gap the other income sources leave — you do not need to fund the same dollar twice. Run it once, end to end: a household spending $150,000 a year that expects $30,000 of Social Security needs $120,000 from the portfolio; at the 4% withdrawal rate defended below, that is . Everything in this section refines that computation — what the expenses really are, what the withdrawal rate should be, and the tax adjustment that pushes the target higher (section “Safe Withdrawal Rate — Why 4%?”).
The expense number deserves the most care, because every dollar of it is levered 25 times. Start with current spending as the baseline — not your salary; your spending. A common shortcut estimates the baseline as salary minus savings minus the costs that end with work (payroll taxes, commuting, the professional wardrobe), then adjusts for the lifestyle you actually intend: downsizing or relocating cuts it, the travel you deferred for thirty years raises it.
Itemize your expected annual expenditures in retirement across all major spending categories:
- Housing Costs (including rent, mortgage, insurance, and taxes).
- Healthcare Premiums and Out-of-Pocket Costs.
- Utilities and Household Operation.
- Food and General Consumables.
- Transportation Costs.
- Taxes.
- Travel, Leisure, and Entertainment.
- Any Other Discretionary Spending.
Retirement spending is not a constant. Plan it in phases:
- Go-Go Years
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The initial active retirement phase with more travel and activities.
- Slow-Go Years
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A subsequent period of moderated spending as mobility decreases.
- No-Go Years
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Potential extended care costs towards the end of retirement — the phase where spending can spike instead of fade (section “Long Term Care Insurance”).
The remaining inputs — inflation (use the 3.5% spending deflator from section “Which Number to Plan With”), life expectancy, tax rates, and portfolio returns — represent analytical assumptions, not established facts; the subsections below show how hard the answer leans on each.