How to Prepare Your FIRE Plan for High Inflation
154 years of US data: high inflation by itself doesn't end early retirements. Rigid spending during it does.
TL;DR
- US inflation is 3.35%, up from 2.4% in February after peaking at 4.2% in May. Most of it is energy: core inflation is 2.45%.
- In 154 years of US data, 4 of 105 fifty-year retirements ran out of money at a 4% withdrawal rate. 3 of the 4 started in a high-inflation decade (1966, 1968, 1969). The fourth was 1929.
- High inflation alone wasn't the problem. Stocks returned 7.6% a year above inflation through the 1940s. The killer was high inflation plus flat stocks, as in 1966–1982.
- A simple rule saved every failed start year: skip the inflation raise after a year your portfolio loses money, and catch up once it recovers. The cost is real: a 1966 retiree would have spent 21% less on average.
The 4% rule raises your withdrawal with inflation every year. That's what makes it safe in normal times and what makes it dangerous in a bad inflationary decade. When prices rise 7% a year and stocks go nowhere, your withdrawals climb while the portfolio shrinks. To see how often that has actually broken an early retirement, we replayed every start year since 1872.
Where inflation is right now
| Measure | Latest | Source |
|---|---|---|
| US CPI, 12 months to August 2026 | 3.35% | BLS via FRED |
| Core CPI (no food or energy) | 2.45% | BLS via FRED |
| Market's 10-year inflation forecast (breakeven) | 2.36% | FRED |
| Brent crude, September average | $101/barrel | Arbat Capital |
| Fed funds rate | 3.75–4.00%, raised in September | Schwab |
The gap between headline and core says this is mostly an oil shock, not inflation spreading through the whole economy. Bond markets expect it to settle near 2.4% over ten years. They expected roughly the same in 2021, the year before inflation hit 9%. A plan should survive the case where the market is wrong.
What 154 years of data show
The method: 100% US stocks (S&P 500 total return) from the Shiller dataset, a 4% first-year withdrawal raised with actual CPI every January, every start year from 1872. It's the same model as the survival heatmap in the Fire Planner. We call a start year "high inflation" when CPI averaged 5% or more over its first ten years: 1909–1916, 1938–1942 and 1965–1980.
| Retirement length | High-inflation starts | All other starts | Failed start years |
|---|---|---|---|
| 30 years | 29 of 29 lasted | 96 of 96 lasted | none |
| 40 years | 27 of 29 (93%) | 85 of 86 (99%) | 1929, 1966, 1969 |
| 50 years | 22 of 25 (88%) | 79 of 80 (99%) | 1929, 1966, 1968, 1969 |
For a traditional 30-year retirement, high inflation never broke the 4% rule in this model. For a 40- to 50-year early retirement, it caused almost every failure.
This model is generous: it takes the withdrawal at year end, after that year's return, and charges no fees. Other methods put the 30-year success rate a little lower (see our 4% rule review). The pattern of which years fail is the same in all of them.
Inflation plus flat stocks is what kills a plan
| Period | Inflation / year | Stocks after inflation / year |
|---|---|---|
| 1941–1952 | 5.9% | +7.6% |
| 1966–1982 | 7.0% | −1.0% |
| 1973–1983 | 8.7% | −2.0% |
| 1872–2026 (all) | 2.1% | +7.1% |
A 1941 retiree saw inflation almost as high as a 1966 retiree's and ended up with six times their starting portfolio after inflation. The difference was what stocks did. A 1966 retiree on the 4% rule had 46% of their starting portfolio left in real terms after ten years, and 28% after sixteen. They were still withdrawing the full inflation-adjusted 4% of the original amount, which by then was over 14% of what was left.
That's sequence-of-returns risk in its purest form. Inflation doesn't need to be worse than the 1940s to hurt you. It only needs to arrive with a decade of flat stocks.
The fix: make your raises conditional
We tested one rule: after a calendar year in which the portfolio lost value, skip that January's inflation raise. Once the portfolio is back above its starting value in real terms, go back to the full inflation-adjusted amount.
| Rule at 4% | 40 years | 50 years |
|---|---|---|
| Always raise with inflation | 112 of 115 lasted | 101 of 105 lasted |
| Skip raises after a losing year, catch up later | 115 of 115 | 105 of 105 |
| Always raise, but start at 3.5% | 115 of 115 | 105 of 105 |
Both fixes work. They cost different people different amounts. Spending after inflation over 40 years, as a % of a fixed 4% withdrawal:
| Start year | Skip-raise rule: average spending | Skip-raise rule: lowest year | 3.5% from day one |
|---|---|---|---|
| 1941 | 99% | 90% | 87.5% every year |
| 1966 | 79% | 54% | 87.5% every year |
| 1973 | 86% | 62% | 87.5% every year |
Starting at 3.5% means a 14% bigger FIRE number, saved for in advance, whether or not the bad decade comes. A $40,000-a-year plan needs $1.14M instead of $1M. The skip-raise rule lets you retire on the smaller number, and you only pay if things go badly. In 1966 the bill was steep: spending eventually fell to about half the original real amount. In most other years you'd barely notice it.
The 54% sounds frightening, but it took a 16-year stretch of falling real values to get there, and that's where flexibility pays off. Someone who retired at 45 can pick up part-time work, cut travel or move somewhere cheaper well before that point. Someone who retired at 65 has fewer of those options. That's why the rule matters more for FIRE than for traditional retirement.
Five more ways to prepare
1. Lock in the first decade with inflation-protected bonds
The first ten years carry most of the sequence risk. 10-year TIPS pay 2.91% on top of inflation, the most since 2008. A TIPS ladder covering your first years pays out in inflation-adjusted dollars whatever stocks do. We covered the numbers in FIRE with 5% bonds. In the US, I bonds are an inflation-linked option too, capped at $10,000 per person per year.
2. Keep a fixed-rate mortgage
Inflation shrinks a fixed debt in real terms. A 3% mortgage taken out in 2021 is costing you less than nothing after inflation right now. Don't rush to pay it off: put spare cash in T-bills at 4.25% instead. A variable-rate loan is the opposite. It goes up with rates, so fixing or paying it down is a priority.
3. Use your own inflation rate, not the headline
CPI is an average basket. A FIRE household that cycles, cooks at home and owns its home outright sees less of the energy shock than a commuter who rents. One whose health insurance renews this autumn will see more: ACA premiums are rising about 15% for 2027. Track your own spending for a year and you'll know which number applies to you.
4. Value income that's indexed to inflation
US Social Security rises with CPI each year; the 2027 increase is forecast at about 3.6%. Delaying a claim gets you a bigger inflation-protected check for life. Pensions without an inflation link lose roughly a third of their value over a decade at 4% inflation. Count them at a discount.
5. Don't hide in cash
Cash at 4.25% beats 3.35% inflation by less than 1% before tax. In 2022, T-bills paid about 2% while prices rose 6.5%. US stocks beat inflation in every 30-year period since 1872; the worst one still returned 3.3% a year after inflation. The answer to high inflation is a flexible spending plan, not a flight from stocks.
Run your own inflation test
The Fire Planner has a High inflation stress test. Set it to 7% for 16 years, starting the year you retire, roughly a 1966–1982 replay, and see whether the verdict changes. You can also give single expenses their own inflation rate: put health insurance or energy at 6% and keep the rest at the default. If the plan only survives without the stress test, decide now which raises you'd skip, so the choice is made before the bad year comes.
Frequently Asked Questions
Yes. The withdrawal rises with CPI every year, so your spending power stays flat. That's exactly why high inflation hurts: the withdrawals grow fast while the portfolio may not. Every failure in our backtest happened with the inflation raise in place.
Cash at 4.25% beats 3.35% inflation by under 1% before tax, and it lost to inflation in 2021–22. Stocks lost about 1% a year after inflation from 1966 to 1982, but they returned 7.6% a year after inflation from 1941 to 1952, when inflation averaged 5.9%. Nobody knows which kind of decade this is. Holding stocks for the long run and inflation-protected bonds for the near years covers both.
It's above the Fed's 2% target and well up from 2.4% in February, but far from the 7% average of 1966–1982. Most of the current rise is energy: core inflation, which excludes food and energy, is 2.45%. The risk for a FIRE plan isn't one bad year. It's a decade of it, which is what the backtest tests.
The backtest uses US stocks and US CPI, so the exact numbers are American. The mechanics carry over: a rule that pauses inflation raises after a bad year protects any withdrawal plan, and most countries issue inflation-linked bonds (UK index-linked gilts, French and German inflation-linked bonds, Canadian real return bonds).
In the Fire Planner, turn on the High inflation stress test and set it to 7% for 16 years starting the year you retire. That's roughly 1966–1982. You can also give individual expenses their own inflation rate, for example a higher one for energy or health insurance.
Stress-test your plan against a 1970s replay.