$2,291,203
Same investable assets at age 48 in both scenarios.
COAST FIRE CONTRIBUTION STUDY
What if you nearly stop saving?The answer is more useful than “yes, you’ve reached Coast FIRE.”
We took the same fictional household retiring at age 58 and cut annual contributions from $45,000 to $5,000. Everything else stayed the same.
THE CONTROL
Only the savings rate changed.
58
Both scenarios stop working at the same age and model retirement through age 95.
$150,000/year
Annual retirement spending stays fixed across the comparison.
$60,000/year
Same annual Social Security beginning at age 67.
THE TRADEOFF
Saving $40,000 less per year did not break this plan—but it did reduce the margin.
637/637 histories lasted
Modeled portfolio at retirement: $4,222,931.
Initial portfolio withdrawal: 3.6%.
637/637 histories lasted
Modeled portfolio at retirement: $3,682,231.
Initial portfolio withdrawal: 4.1%.
-$540,700
Reducing annual contributions by $40,000 left about $540,700 less modeled capital at retirement.
+0.52 percentage points
The initial portfolio withdrawal rate rose from 3.6% to 4.1%.
WHY THIS MATTERS
Coast FIRE is better treated as a tradeoff surface than a finish line.
A binary Coast FIRE calculator answers a useful first question: could your existing investments grow enough to support a future retirement target without additional contributions? But real decisions rarely stop there. Someone might want to save less, take a lower-paying job, work fewer hours, or redirect cash toward life now.
In this example, cutting annual contributions from $45,000 to $5,000 still produced 637 surviving histories out of 637. The tradeoff was not “retirement works” versus “retirement fails.” It was roughly $540,700 less modeled capital at retirement and a higher initial withdrawal rate.
That is a much more decision-useful way to think about Coast FIRE: not “am I done saving?” but “how much margin am I willing to trade for more flexibility today?”
METHODOLOGY & LIMITS
This is a controlled historical stress test, not a universal Coast FIRE rule.
One variable changed
Starting assets, retirement age, retirement spending, Social Security, life expectancy, and allocation remain the same. Only annual contributions change.
637 overlapping tests
The scenarios use historical U.S. returns from July 1926 through June 2026 and 47-year windows.
637/637 is not a guarantee
The historical windows overlap, and future returns, inflation, taxes, spending, and income can differ from the tested record.
Margin still changed
Even though both scenarios survived every tested history, their retirement assets and withdrawal pressure were materially different.
For the simple threshold calculation, use the Coast FIRE calculator. For the broader retirement stress test, use the retirement calculator or browse all Ask Linc research.
START WITH THE DECISION
What could you change once saving becomes optional?
Explore my planTry free for 30 days. No credit card required.