How Long Will Your Retirement Money Last? Withdrawal Rates, Sequence Risk, and the Annuity Decision

Accumulating a retirement corpus is solved by compound growth. Making it last 30 years is a different problem entirely.

The retirement calculator helps you build the pot. A separate set of decisions — how much to withdraw, in what sequence, from which accounts — determines whether that pot lasts one decade or four. Sequence of returns risk, withdrawal rate selection, and the annuity vs drawdown choice are the decisions that matter most after you stop accumulating.

Sequence of returns risk: why the first decade matters most

Two investors retire with £500,000 each. Both average 6% annual return over 20 years. They withdraw £25,000/year. The outcome should be identical — it isn't.

Investor A: poor returns in years 1–5, then recovery Year 1–5: -10% average Year 6–20: +12% average → Portfolio depleted in approximately year 14

Investor B: good returns in years 1–5, then decline Year 1–5: +15% average Year 6–20: +2% average → Portfolio lasts approximately 25+ years

Same 20-year average, same withdrawal rate, completely different outcomes. The difference: when you're withdrawing money and markets fall, you're selling units at low prices — permanently reducing the number of units available to recover. Bad early returns have a disproportionate permanent impact.

Implications:

• A "safe" withdrawal rate is defined by the worst historical sequence, not the average
• Reducing withdrawals in early down years preserves far more than equivalent cuts later
• Having 1–2 years of cash/short-term bonds as a buffer avoids selling equities during downturns

The 4% rule and its limitations

The 4% withdrawal rule is a useful starting point but has specific parameters:

• Based on US historical data (1926–present)
• Assumes a 30-year retirement
• Assumes 50–75% equities, rest bonds
• Assumes static withdrawal increasing only with inflation

Where it may fail:

• Retirements longer than 30 years (early retirees need 40–50 years of sustainability)
• Non-US markets with lower historical returns
• Current starting valuations (starting from high CAPE ratios historically predicts lower subsequent returns)
• Prolonged low-return environments

More conservative alternatives:

• 3.5% rule for 40-year retirements
• 3% rule for 50-year retirements (FIRE early retirees)
• Flexible withdrawal strategies that reduce spending in bad years

Flexible withdrawal strategies

Guardrails method (Guyton-Klinger):

• Start at 5.2–5.5% withdrawal
• If portfolio grows 20%+ above initial value: allow spending increases
• If portfolio falls below threshold: cut spending by 10%
• Produces higher initial withdrawals but requires flexibility

Floor-and-upside: divide spending into:

• Floor: essential non-negotiable spending (housing, food, healthcare) — funded by guaranteed income (state pension, annuity)
• Upside: discretionary spending — funded from portfolio; flexible in bad years

Variable percentage withdrawal: instead of fixed £ amount, withdraw a fixed % of the portfolio each year. Income fluctuates with market performance but the portfolio essentially never runs out mathematically. Drawback: income volatility may be uncomfortable.

Annuity vs drawdown

Annuity: exchange a lump sum for a guaranteed income for life (or fixed term). Eliminates longevity risk and sequence risk. In exchange: no access to capital, no inheritance, no upside if markets do well.

Drawdown: keep your pension invested, draw income as needed, retain flexibility and potential upside. Subject to longevity risk and sequence risk.

Annuity rates (UK, approximate 2024): For a 65-year-old, £100,000 buys approximately £6,500–7,000 per year (level annuity, no escalation). Inflation-linked annuity: approximately £4,200–4,800 per year (lower starting income because it grows with inflation).

The annuity break-even: At £6,750/year from £100,000: you've received your money back in approximately 14.8 years. If you live to 65 + 14.8 = 79.8 years, the annuity starts "winning." UK male life expectancy at 65 is approximately 84 — meaning most men who reach 65 live past the break-even point.

The hybrid approach: annuitise enough to cover essential floor spending (state pension + partial annuity covers necessities), keep the rest in flexible drawdown.

How to use the Retirement Calculator on sadiqbd.com

1. Calculate your target corpus — the accumulation side
2. Test withdrawal scenarios — what annual income does your corpus support at 3.5%, 4%, 4.5% withdrawal?
3. Model the floor — how much does your state/workplace pension provide? The gap is what drawdown/annuity must fund

Frequently Asked Questions

What is a "sustainable" withdrawal rate in today's environment? Research from Morningstar (2023) suggests a starting safe withdrawal rate of 3.8% for a balanced portfolio over a 30-year retirement in a "moderate" market outlook scenario. For very long retirements (40+ years), 3.5% or lower is more prudent.

Does it make sense to have both an annuity and drawdown? Many UK financial planners recommend this for the security it provides. Annuitising enough to cover essential needs eliminates the anxiety of a falling portfolio while the drawdown portion retains flexibility and growth potential.

Is the Retirement Calculator free? Yes — completely free, no sign-up required.

Try the Retirement Calculator free at sadiqbd.com — calculate your corpus target, monthly savings needed, and how long any corpus will last at different withdrawal rates.