Also called: Guyton-Klinger rules, Guardrail withdrawal strategy.
Guardrails sit between the two extremes of retirement spending. A fixed real dollar rule ignores markets entirely and puts all the risk on the portfolio. A fixed percentage rule tracks markets exactly and puts all the risk on your lifestyle. Guardrails do neither most of the time and both at the edges.
The mechanic is simple. You compute the current withdrawal as a percentage of the current balance. If markets have fallen far enough that this rate breaches the upper guardrail, spending is cut by a set amount. If markets have run far enough that the rate falls under the lower guardrail, spending is raised.
The appeal is that adjustments are rare, pre-committed and small. Rather than reacting to every wobble, you agree in advance what would have to happen before you changed anything — which is a far easier decision to make years ahead of the moment than in the middle of a crash.
The catch is that a guardrail rule is only real if the cut is actually available. If nearly all your spending is fixed costs, a rule that instructs a 10% reduction cannot be followed, and the plan reverts to the rigid case with extra steps.
Research on this
- Is the 4% Rule Still Safe? We Ran 5,000 Simulated Retirements
- Which Investing Strategy Wins? Six Strategies Benchmarked on the Same Markets
See also
- Safe withdrawal rate — The share of a portfolio’s starting value you can withdraw in year one of retirement, then raise with inflation each year, without running out over your horizon.
- The 4% rule — A rule of thumb from William Bengen’s 1994 research: withdraw 4% of the portfolio in year one of retirement, then raise that amount with inflation each year.
- Decumulation — The phase in which a portfolio is being spent rather than built, and the set of decisions — how much to withdraw, from which accounts, in what order — that go with it.