Direct answer: At 100, the financial planning horizon is 5 to 10 years, not 1 to 2 years. Roughly one in four people who reach 100 live past 105. A plan built only on the average will fail those who live longer. The planning horizon should extend to age 110 for someone in reasonable health at 100.
How Long to Plan at 100: The Longevity Reality
Life Expectancy at 100: What the Data Says
Average remaining life expectancy at 100 in the United States is approximately 2.5 to 3 years, based on Social Security Administration actuarial data. This means the average centenarian dies at roughly 102 to 103. However, this average includes everyone who reaches 100, including those who are already very frail or in terminal illness at the time they turn 100.
For a centenarian in reasonable health, the probability of surviving significantly longer than the average is meaningful. Roughly one in four people who reach 100 survive past 105. One in twenty survive past 110. These probabilities are not negligible. A financial plan built only on the average will fail approximately 25% of those it covers, and the consequences of failure (running out of money while still alive) are severe.
The appropriate planning horizon at 100 is therefore 5 to 10 years, not 2 to 3 years. Planning to age 110 from age 100 means planning for a decade, which is a shorter horizon than at 80 but still long enough that inflation, care cost escalation, and investment allocation all matter.
What a 10-Year Horizon Means in Practice at 100
A 10-year planning horizon at 100 has specific implications. Inflation over 10 years at 3% reduces purchasing power by approximately 26%. If care costs are 8,000 dollars per month today and inflate at 4% annually, they will be approximately 11,844 dollars per month in 10 years. A plan that does not account for this escalation will run short even if the person does not outlive their assets.
Required minimum distributions at this age are so large (17% or more of the IRA balance per year) that the traditional IRA will be depleted within a few years in most cases. The question of what happens when the IRA is gone must be planned for: will there be taxable assets, pension income, Medicaid eligibility, or another source of care funding?
Social Security income, which is not depleted and is inflation-indexed, becomes proportionally more important at 100 as IRA assets deplete. Ensuring that Social Security is being received correctly and at the maximum amount (particularly if a spousal benefit is available and has not yet been claimed) is a useful early step in the annual review.
Longevity Risk at 100: A Different Shape
Longevity risk at 100 has a different character than at 70 or 80. At 70, the risk is primarily portfolio-related: will the investment portfolio generate enough income for a 20-30 year retirement? At 100, the portfolio risk is largely resolved by high RMD distributions: the traditional IRA will be substantially depleted by natural death in most cases.
The longevity risk at 100 is primarily care risk: will the assets (whatever remains after years of RMDs and care costs) be sufficient to fund care if the person lives to 105 or 110? This is a specific, quantifiable question. The answer depends on current assets, current care costs, expected cost inflation, and the expected trajectory of asset depletion through RMDs.
For people where the math suggests assets may run short before death, Medicaid long-term care planning becomes relevant. Medicaid pays for nursing home care for people who have spent down to Medicaid asset limits (which vary by state but are typically very low). An elder law attorney can model whether and when Medicaid eligibility becomes relevant and what steps, if any, can be taken to preserve assets while still qualifying.
Frequently Asked Questions
What is the life expectancy at age 100?
Average remaining life expectancy at 100 in the United States is approximately 2.5 to 3 years, putting the average age at death around 102 to 103. However, roughly one in four centenarians survive past 105, and roughly one in twenty survive past 110. For financial planning purposes, a 5-10 year planning horizon (planning to age 105 or 110) is appropriate to protect against running out of money for the portion of centenarians who live significantly longer than the average.
Should a 100-year-old plan for 10 more years?
Yes. Planning to age 110 from 100 is the actuarially sound approach for a centenarian in reasonable health who cannot know their remaining lifespan. Roughly one in four people who reach 100 survive past 105. A plan that assumes death at 102 or 103 (the average) will fail approximately 25% of the people it covers. A 10-year planning horizon accounts for care cost inflation, IRA depletion through RMDs, and what happens when IRA assets are exhausted.
How does longevity risk affect financial planning at 100?
At 100, longevity risk is primarily care risk: will assets last long enough to fund care through a longer-than-average lifespan? The traditional IRA is typically being depleted rapidly through large mandatory RMDs. If care is expensive and the person lives past 105 or 110, assets may run short. An elder law attorney can model this trajectory and evaluate Medicaid eligibility planning for situations where assets may be exhausted before death.