The 4% rule has one big weakness: it keeps spending the same amount whether markets are booming or crashing. Guyton-Klinger guardrails fix that with two simple rules that react to what your savings are doing.
What Guyton-Klinger Actually Does
Jonathan Guyton and William Klinger published their "decision rules" in 2006. The two best known are the guardrails:
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Each year, look at your withdrawal rate: this year's spending divided by your current savings.
annual withdrawal ÷ current savings -
Capital preservation rule. If that rate has risen more than 20% above your starting rate, cut spending by a fixed percentage (10% in the original).
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Prosperity rule. If it has fallen more than 20% below your starting rate, raise spending by a fixed percentage.
With a 5% starting rate, the guardrails sit at 6% and 4%. While your withdrawal rate stays between them, spending just follows inflation. When it crosses one, spending steps down or up, and inflation adjustments continue from the new level. (The original paper adds a few more rules, such as skipping the inflation increase after a losing year; the guardrails are the heart of it.)
That is the whole strategy: a feedback loop with two thresholds. No forecast, no judgment call.
See It Against the Alternatives
The lab below spends the same savings four ways over the same 25 years of returns. The guardrails line follows the rules above: cut 10% when the withdrawal rate rises 20% above where it started, raise 10% when it falls 20% below, and never below half of the starting spending. Switch between "bad years first" and "good years first":
Try it
Four ways to spend from your savings
The same savings and the same 25 years of returns, spent four different ways. Switch the order of the returns to see which rules hold up when the bad years come first.
| Rule | Lowest year | Total spent | Left at end |
|---|---|---|---|
| Fixed | 45,000 | 1,125,000 | 187,708 |
| Guardrails | 32,805 | 843,660 | 755,483 |
| % of savings | 28,696 | 841,218 | 801,899 |
| Floor & ceiling | 33,750 | 855,715 | 743,977 |
Starting spending: 45,000 a year.
Free, no account needed. Opens the fixed version with 1,000 possible futures instead of one made-up sequence (spending after a 20% tax, so about 80% of the withdrawal). Guardrails, % of savings and floor & ceiling are Pro strategies in the simulator.
Made-up returns after inflation (average 4.1% a year), so every amount is in today's money. Guardrails cut 10% or raise 10% when the withdrawal rate moves 20% away from where it started, and never go below half the starting spending. Floor and ceiling: between 75% and 125% of the starting amount. Before tax, no pensions.
Two patterns show up. When the bad years come first, fixed spending keeps paying the full amount and ends with far less left, while guardrails trim spending in the rough years and keep more invested for the recovery. When the good years come first, guardrails raise spending and you enjoy more of the gains. You trade a steady income for a plan that bends instead of breaking.
Why It Works
The cuts arrive exactly when they are most useful: early in a downturn, when savings are down and every sale locks in a loss. That is sequence-of-returns risk at work, and a fixed rule has no defense against it. In good markets, guardrails behave much like a fixed rule, with an occasional raise.
Because of this, a guardrails plan can usually start with a somewhat higher withdrawal rate than a fixed plan and still hold up as well. How much higher depends on your savings, your mix of investments and your assumptions - which is why it is worth running your own numbers rather than borrowing someone else's rate. For one set of numbers, guardrails vs the 4% rule compares starting rates and what each plan spends 10 and 20 years in.
Choosing the Settings
Cut size. A 10% cut is the classic choice. Bigger cuts protect the savings more but make bad years feel worse. Smaller cuts are gentler but do less each time.
Raise size. Raises let you enjoy good markets, but every raise increases what you will need to cut later if markets turn. Retirement Lab starts with no raises by default, which is the cautious choice.
A floor. Unlimited consecutive cuts could push spending uncomfortably low in a long bear market. Retirement Lab never lets guardrail spending fall below half of your starting amount.
When Guardrails Are Not Enough
High fixed costs. The cut applies to total spending. If most of your budget is housing and healthcare, a 10% overall cut is a much bigger cut to everything else. A floor-and-ceiling approach, or pension income that covers fixed costs, may fit better.
Long flat markets. A decade of poor returns can trigger cut after cut. The plan survives on paper; living on it is harder.
Actually following the rules. Guardrails only work if you make the cuts when they are due. Skipping them in bad years quietly removes the protection.
What This Means for Your Plan
Compare guardrails with fixed spending on your own plan. Same savings, same assumptions, two strategies - and look at both the success rate and what you would actually get to spend.
Keep a cash buffer. A year or two of spending in cash lets you ride out the first months of a crash before a cut kicks in.
Stress-test the worst timing. Add a crash right after you retire and see whether the rules hold.
Make the rules a commitment. Running the plan in advance shows you what a cut looks like in real numbers, which makes it much easier to follow through when it happens.
Guyton-Klinger guardrails are one of the Pro spending strategies in Retirement Lab, alongside percentage of portfolio and floor and ceiling.
Frequently Asked Questions
- What is the Guyton-Klinger withdrawal strategy?
- A flexible way to spend from your savings with two guardrails. If your withdrawal rate rises too far above where it started (because the savings fell), you cut spending by a set percentage. If it falls too far below (because the savings grew), you raise it. In between, spending simply follows inflation.
- How does Guyton-Klinger compare to the 4% rule?
- The 4% rule spends the same inflation-adjusted amount every year, whatever the market does. Guardrails cut spending after bad stretches and raise it after good ones. That usually lets the money last longer - or lets you start a bit higher - at the price of an income that moves. The best way to compare is to run both on your own plan.
- What cut and raise percentages should I use?
- Guyton and Klinger's original rules used 10% adjustments with guardrails 20% either side of the starting withdrawal rate, and that is a common starting point. Bigger cuts protect the savings more but make your income less stable. In Retirement Lab the guardrails are fixed at 20%, the cut and raise percentages are yours to set (10% and 0% by default), and spending never drops below half of your starting amount.
- Can I use Guyton-Klinger if I have fixed expenses I cannot cut?
- Only partly. The cut applies to total spending, but some costs - housing, healthcare - are hard to trim. If only 40% of your spending is flexible, a 10% total cut means a 25% cut to that flexible part. A floor-and-ceiling approach, or a pension that covers the fixed costs, may fit better.
Now try it with your own numbers
An example plan is filled in - change anything, then open it in the free simulator.
Opens the free simulator with these numbers filled in - check them and run it. Nothing is stored unless you create an account and save.