Does Your Windfall Let You Coast to FIRE?
Example: Current retirement savings: 150000 $ · Windfall (after tax, going to retirement account): 80000 $ · Current age: 38 years · Target retirement age: 65 years · Target annual retirement spending: 80000 $ · Expected annual return: 7 % · Safe withdrawal rate: 4 %
| Already at Coast FIRE? (1=yes) | 0 |
| Coast FIRE number needed today | $321,861 |
| Your total after windfall | $230,000 |
| Projected value at retirement | $1,429,190 |
Worked example
A 38-year-old with $150,000 saved adds an $80,000 inheritance to reach $230,000. FIRE number ($80K spend / 4% SWR) = $2,000,000. Coast FIRE target at 7% for 27 years = $2,000,000 / 1.07^27 = $342,000. At $230,000 they are not coasting yet — shortfall of $112,000. But at $342,000 they can stop contributing entirely and reach $2M at 65. The windfall moved them more than halfway to the coast.
Frequently asked questions
What is Coast FIRE exactly?
Coast FIRE is the portfolio balance at which compound growth alone — with no additional contributions — will reach your full FIRE number by your target retirement age. Once coasting, you only need to cover living expenses from your current income, not save anything extra.
What safe withdrawal rate should I use?
The 4% rule (Trinity Study) is the standard starting point. For retirements longer than 30 years or starting before age 55, some planners use 3–3.5% to build in more buffer. For a conservative 30-year horizon starting at 65, 4–4.5% is widely used. The rate you choose directly affects the size of your required FIRE number.
Can I put a windfall into a retirement account directly?
Annual contribution limits apply: $23,000 to a 401(k) in 2024, $7,000 to an IRA ($8,000 if 50+). If your windfall exceeds these limits, the excess must go into a taxable brokerage account. You can still invest it for retirement — you just lose the tax shelter.
Does reaching Coast FIRE mean I can stop working entirely?
No — it means you can stop contributing to retirement savings. You still need earned income to cover day-to-day expenses until retirement age. Many Coast-FIRE households downshift to lower-stress, lower-paying work, or part-time work, since the retirement nest-egg pressure is removed.