A hamster in a wheel with the caption enough of this already.

Thus far we’ve explored why the 4% rule doesn’t work in the real world, and established a more sustainable withdrawal rate (SWR) for UK / global investors. Please read those articles if you’ve not already done so, in order to get the most out of this piece.

Now for the good bit! We’re going to talk about why you can use a higher SWR if – and only if – you’re prepared to execute a withdrawal plan that’s considerably more sophisticated than the 4% rule.

To raise our SWR we’re continuing to use the layer cake concept advocated by leading retirement researchers William Bengen and Michael Kitces.

The layer cake personalises our SWR by applying a suite of plus and minus factors.

  • The last post was all about the bad stuff. We saw how it forced my SWR down to 3%.
  • Now I’m going to layer on all the positives, and test my approach using global historical data.

Without wanting to ruin the surprise, I was pretty shocked by the results you’re about to see and I think I’ll need to be more cautious than the test suggests when the rubber really hits the road.

Even Kitces is very clear about the layer cake’s limitations:

Although the ‘layer cake’ approach of safe withdrawal rates does allow for planners to adapt a safe withdrawal rate to a client’s specific circumstances, there are several important caveats to be aware of.

The first and most significant is that many of the factors discussed here were evaluated in separate research studies, and it is not necessarily clear whether they are precisely additive.

Okay, so remember my SWR is currently bottomed out at 3%.

Let’s head for the top!

Diversification sweetener

Our baseline SWR assumes we’re invested in a Developed World 50:50 equity / bond portfolio. Yet there’s plenty of evidence that a stronger equity tilt and more diversification increases your SWR, especially over longer time horizons.

The shotgun spread of long-term equity returns means that an equity-heavy portfolio can shoot the lights out sometimes. However it also falls far short of the target on unlucky occasions. Bonds can staunch the bleeding when equities haemorrhage, yet too much bondage may also cripple you over time.

Early Retirement Now (ERN) sums up the dilemma:

Stocks have a lot of short-term risks, but in the long-term stock returns are tied to economic growth and thus, in the very long-term, real returns become less risky due to that.

Bonds have relatively little short-term risk around their trend growth rate, but their trend growth path itself has a lot of risk in stark contrast to stocks.

The answer isn’t to simply load up 80-100% in equities and hang on for dear life. Rather we can aim to alter our asset allocation as we go.

Michael McClung in his brilliant retirement portfolio book, Living Off Your Money, recommends an eve-of-retirement bond allocation of 50% for a 30-year time horizon, or 55%-65% for longer stretches.

The reason for starting retirement with a heavy bond load is that you’re particularly susceptible to sequence of return risk in the closing years of accumulation and the opening decade of deaccumulation. You can protect yourself during this period with high-quality government bonds.

Kitces has shown how an ill-timed stock market crash can setback your retirement plans like an asteroid strike scuppered talking dinosaurs. He also explains how the sequence of returns in the first 10 to 15 years of your retirement can seal your fate for good or bad.

It’s important to have enough bonds to deal with these threats, and to deploy your bonds effectively.

McClung in particular has developed techniques to help you do this – see the ‘dynamic asset allocation’ section below. The trick is that you allow your bond allocation to wax and wane according to market conditions.

More generally, the historical data sampled by Kitces, Bengen, McClung and others tells us that broad diversification beyond bonds works in retirement just like it does during the accumulation phase.

They cite evidence in favour of diversifying your retirement portfolio with:

Kitces offers a diversification bonus of +0.5% SWR for significant multi-asset class diversification. It seems daft not to take it.

The Accumulator’s layer cake SWR:

3% + 0.5% diversification = 3.5%

Dynamic asset allocation

The best way to protect yourself from sequence of return risk? Live off your bonds when equities are down.

Beyond that you can further improve your portfolio’s life expectancy by using a rebalancing method that increases equities exposure when they’re seemingly cheap, and only replenishes bonds when equities have seriously outperformed.

This is dynamic asset allocation. It’s a super-charged version of ‘buy low, sell high.’ You can read about McClung’s version – called ‘Prime Harvesting’ – by downloading a free sample of his book.

Techniques such as dynamic asset allocation will test your risk tolerance because in extreme market conditions you may eat all your bonds and end up 100% in equities. Steer clear if you’re cautious.

Otherwise Kitces awards 0.2% to your SWR for dynamic allocation.

The Accumulator’s layer cake SWR:

3.5% + 0.2% dynamic asset allocation = 3.7%

Flexible spending and dynamic withdrawal rates

Here is the big SWR cherry on top. If you can cut your spending during a downturn then you gain a massive advantage over a constant inflation-adjusted withdrawal plan.

Dynamic withdrawal rates mean you adjust your spending in sympathy with your portfolio’s fortunes. Like managing a forest, being able to conserve your resources when they’re under stress is obviously more sustainable than consuming an ever greater percentage when the rot sets in.

Flexibility is key. Retirement researchers have devised all kinds of rules that allow you to spend more when the market soars, but you must also spend less when there’s trouble at mill.

McClung does a masterful job of analysing various dynamic withdrawal rates in his book, while ERN has written a sobering series exploring how much you might have to cut back using one of the better known spending systems.

In practice, cutting back is what all retirees do if their money runs short. The risk is that extra spending early in retirement may force us to spend less later if the cookie doesn’t crumble our way.

That gamble may be easier to take if you believe that retirees spend less later in life. What do you reckon? The evidence is patchy and may not apply to you. I’ve read research that concludes retirees spend more if they have it, but spend less on average because most end up with less to spend.

Kitces’ flexible spending modifier:

  • +0.5% SWR for modest spending cuts in bear markets and/or plan to decrease spending in later life.
  • +1% SWR for substantial (10%+) spending cuts in bear markets and/or plan to make significant cuts in later life.

I think Mrs Accumulator and I can handle 20% spending cuts so I plan to use Michael McClung’s EM dynamic withdrawal rules. Our State Pensions should meet near 70% of our estimated outgoings later on. I’m gonna claim the full 1% bonus!

The Accumulator’s layer cake SWR:

3.7% + 1% flexibility bonus = 4.7%

My new world portfolio SWR

My personal SWR was creamed by negative factors in the last post. It finished up at just 3%.

Now it stands at 4.7% and I’m stunned.

What does it all add up to in cold hard cash?

Well, we’d like an annual retirement income of £25,000, so our retirement wealth target at 4.7% SWR is:

(1 / 4.7) x 100 x £25,000 = £531,750

In contrast our target at 3% SWR was £833,333, which was 57% higher.

Wow. Just wow.

If I use the ‘4.7% rule’ then we’re FI already!

The sniff test

The big question is does this layer cake business pass mustard?

The research shows that your SWR changes dynamically as you shift the parameters. I can test these moving goalposts using global historical data thanks to the fantastic Timeline app.

Timeline is commercial software created by retirement researcher Abraham Okusanya. It’s aimed at financial planners who want to model portfolio withdrawal plans.

Timeline is very well designed, loaded with great features, and delivers the Holy Grail of global / UK appropriate datasets. I think it’s worth paying an IFA to run your numbers through it if they have access.1

My 4.7% SWR achieved a 99% success rating on Timeline – success means historical me didn’t run out of money in 99% of scenarios.

The bottom 10% of scenarios did require me to cut spending drastically to actually avoid running out of money though. That may not be your idea of success.

On the other hand, every path above the 10th percentile was comfy, and the best case scenario near-tripled my income for years. I used all the layer cake assumptions – good and bad – to get the result but was able to leave our State Pensions in reserve.

However that doesn’t tell me that my 4.7% rule is safe or even sustainable. We live in the future, not the past. I won’t experience the historical data in retirement, though hopefully I won’t face anything worse.

The truth is that a lower SWR is safer no matter how much kung-fu you know, so I’m not actually going to adopt a 4.7% SWR.

4% it is

So after everything we’ve been through I’m going to choose 4%.

Editor: You clutz! You total time-waster! Is this your idea of a joke?

Okay look, it’s thousands of words later and I’m as aghast as anyone, but I’m not using that 4% rule.

  • I’d have to use a 3% SWR to live with naive, constant inflation-adjusted rules.
  • But 4% with all the layer cake trimmings works with McClung’s system and it comfortably performs in Timeline.

In short, I am only happy to choose 4% because it leaves me room for manoeuvre when allied with the withdrawal techniques we’ve touched on in this series.

I also have – and must have – a Plan B.

Maybe my ability to use complex techniques will ebb through my eighties and nineties? Maybe I won’t even make it that far – a big problem given Mrs Accumulator’s interest in dynamic withdrawal rates continues to hover around zero. (“But look, they’re dynamic!”)

Plan B is to switch to a simpler, safer Floor and Upside strategy when our State Pensions kick in and annuity rates tip in our favour.

Aside from that we’ll maintain an emergency fund, there’s always the house to sell or reverse mortgage, and there are side hustles to hustle if we have to.

More than anything, digging into the research has taught me that a SWR is a very personal number. Like inside leg measurement personal. And it’s probably not even a number.

Really, it’s a floating set of coordinates that give you something to aim for. Your final destination can only be known when you arrive.

Take it steady,

The Accumulator

  1. For a fixed fee of course.

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