22 Oct 2015, 9:01pm
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  • Compound Interest won’t help you retire early, but it may help you afterwards

    I’ve always been the cynic on the practical value of compound interest – while it will probably will more than double the real value of a conventional retiree’s retirement savings by the time they get to retire, it’s not magic. The problem is we don’t live long enough, we don’t work long enough, particularly in the PF favourite occupations of finance and IT, and more to the point, particularly for young folk compared to me, you get some serious career progression which means you can save more money as time goes by.

    career progression is much faster now

    career progression is much faster now

    Money is fungible – it doesn’t matter that your pension pot has £1000 from the £180 you saved when you were 25 with a paltry 20% tax lift, boosted by compounding, or £1000 from the £600 you saved in a month when you were 45 and paying 40% tax. It still adds up the same. All the old saws about Sensible Susan saving for 10 years ‘twixt 20 and 30 before she has kids never to save into a pension again doing better than Erratic Eddie who only started when he was 30 are bollocks unless you assume unrealistically high real rates of investment return or very long working lives. A long working life is something that by definition the FI/RE crowd don’t want to have.

    Unrealistic Investment returns

    Before you assume a 10% real terms return from investments ask yourself why that slack bastard Warren Buffett is only good for 13% p.a. average, I was wrong here he’s good for 19%. But he says you are only good for 6-7% nominal, 3-4% real. Bear in mind that the sequence of returns matters – take a hammering at the end and it’s worse than taking a hammering at the start. Cautious fellows like RIT are pushing down the safe withdrawal rate below 4%, the SWR is a proxy for the real investment return modified by the sequence of returns risks. Although you are slightly insulated from sequence of returns risk while you ware working (you can always work one more year for comfort and all that) compare to your retired self, assuming you can do better than twice the average real return year on year steadily is making an exceptional claim. You only get the exceptional evidence to back up that exceptional claim just before you retire. There’s no go-around again option by then.

    Long working lives

    One observation is supportive for this – we live a lot longer now than a few decades ago, possibly up to 10 years longer, and by observation while sitting on our backsides in offices gives us lardy arses the middle-aged of today just don’t seem to carry the burden of musculoskeletal aches and pains of the manual workers of my father’s generation, and arthritis and respiratory diseases are far less common than the middle-aged adults I knew as a child. There is some sample bias in my observation – I grew up in a working-class community but worked and lived in a community of people who didn’t work with their hands, but I would say that in general we are fitter but fatter in middle age than earlier generations.

    The trouble is that to have a long working life there has to be work you can and ideally want to do throughout that long working life. I managed 30 years before I got pig-sick of the way the workplace was changing, and I didn’t even work in the those favourite PF occupations of IT and finance both of which seem to burn people out before they clear their forties nowadays. My Dad worked from 14 to 65, over 50 years, I only managed thirty. Anybody who wants to retire early isn’t going to have a long working life, and the value of compounding depends critically on the amount of time it is given to work.

    Another problem is that the pace of change is faster now. Experience accumulated over a working life counted for more in the past. Much of what I learned as a young pup is absolutely worthless now – things like timing the studio cameras to be synchronous and in colour phase at the vision mixer is just irrelevant to anything now, though it was handy to know 30 years ago. As such you may have trouble in commanding higher pay later in life in technical fields, although it is still true that leading people is a skill that improves with age. But organisations have flatter hierarchies now, the levels in the pyramid are further apart. And anyway, TEA gives it to you straight between the eyes

    the underlying purpose of work…which was to fund getting the fuck out as quickly as possible.

    which sort of goes against doing it long enough for that compound interest malarkey to make the saving easier. Compound interest is the principle behind most people’s approach of only saving less than 25% of their pay to a pension. They get a nice long working life, or suffer an extreme income hit when they stop working.

    This is why compound interest won’t help you, FI/RE wannabee

    I worked for 30 years, which is an old lag in the FI/RE universe – although I had a decent job it wasn’t one of those finance/IT ones (I did some IT but it was peripheral). Many of you are targeting a 20 year working life, which is a good call, look around your office and ask yourself how many 45 year-olds and up are there? If a normal working life is 21 to 67 these days  then just under half your colleagues 1 should be over 45. If you don’t see that many older employees, then don’t count on a long working life in that industry.

    Monevator’s compound interest calculator tells me at a real interest rate of 4.5% your starting contributions will be increased to 2½ times their value over 20 years. If you look at the ONS chart you expect to get a tripling of salary over your short career – it took me over 30 years to get the career progression that seems to happen in half that time nowadays. So your increased later monthly savings will probably beat out the value of compound interest on your early monthly contributions. Plus at the moment the old git gets more help/shafted less by the taxman than the young fellow – I experienced this directly, it’s much cheaper  to save to a pension with a 40% tax boost than a 20% boost. You still need those early contributions, every little helps and all that, but forget that story of Sensible Susan quitting at 30. The only reason that could work is if she works (ie not drawing down) until she is 67 and enjoys a higher than excepted investment return. That ain’t likely – secular stagnation would seem to be lowering investment expectations, not inflating them. And who wants to work to 67? Not you, FI/RE aspirant.

    Who does compound interest work for?

    Entities with long investment horizons. Preferably ones that are longer than a human lifetime, because at realistic rates of return on capital, that’s how long you need for it to shoot the lights out. Apparently there’s something called Downton Abbey on t’telly, and The Escape Artist deconstructs the compound interest message from there. Basically get on the side of Capital – either by earning a shitload more money than most but not living an extravagant lifestyle, or alternately get your ancestors to work for your capital and live off the income it generates. Decency would suggest you don’t spend more than the income, so that you can gift your idle spawn the same gift your ancestors handed you. This doesn’t work well in a world of rapidly increasing human population and increased capital from non-human work, specifically fossil fuels, but it worked tremendously well for a lot of human history. Okay, it worked well for the aristocrats, rather than most people.

    One of the interesting things in the comments on TEA’s article is where parents try and teach their children how compound interest works. Observe how they have to create absolutely unrealistic accounts where Daddy pays a whopping 10% p.a. interest rate to make the story ‘interesting’ enough to attract any attention. Look at how long you have to go back in time to when the Bank of England interest rates were that much – nearly a quarter of a century! That was a special case when Soros was ejecting Britain from the ERM. And look at when interest rates hit 10%+before in the late 1970s – the Ermine was still at school then. And remember what else happened then – we had inflation running at 27% annually at one point, so that 10% interest was still a dead loss. It’s a totally unrealistic rate, and they aren’t going to get that sort of interest unless all sorts of other shit is going down in the economy at the same time.

    Now I know that you often have to simplify and amplify things for pedagogic reasons, because children are simple-minded with short attention spans, but in the end you’re teaching a lie. The difference between 5% annual return and 10% annual return is stupendous 2. This is similar to other lies people tell children to make them believe the world is other than it really is, like Father Christmas and the Tooth Fairy. It’s a good story. But it’s not true. You sometimes have to tell children lies like that, but as adults you should have grown out of such fantasies about compound interest in the same way as hopefully you don’t still believe in Father Christmas.

    Compound interest, if positive and greater than inflation, can give you any amount of money you want. The catch is you have to wait long enough for it to work its magic, and 20 years is enough for a doubling, but not a tripling, at typical real rates of return of the riskiest commonly available asset class with the best long-term historical performance. Of course a doubling is worth having. But it’s not life-changing. Also bear in mind if you carry any debt at all during your working life then that is compound interest working against you. Debt includes a mortgage – you pay roughly twice the real price for a house in the long run at typical British long-term mortgage rates, which funnily enough, happen to be around the 6% mark. The only thing that makes that acceptable is you’d otherwise be paying rent for that time, and even then it takes a long time to break even.

    In comparison, just under a thousand years ago a lot of people accumulated a shitload of capital in the UK, because William the Conk stole it from the previous owners and gave some of it to his mates who aided and abetted the heist. Compound interest worked for them – the aristocracy still owns more a third the land in England, much of which has remained in the same families’ hands for the last 200 years. You’re looking at compound interest at work – it paid for each generations huntin’ and fishin’ and all those servants to make their life easier than the rest of the country.

    No wonder that the middle classes, observing the twin forces of automation and globalisation destroying many of the jobs they hoped their sons and daughters would go into, are bitching like hell to get inheritance taxes reduced so they can featherbed their kids against the incoming economic storms. Get on the side of capital. It sure beats the hell out of working for a living, and it’s doubly sweet if you didn’t have to earn the capital in the first place.I mean FFS, let’s make the middle class’s houses IHT free as they peg it so their children don’t need to work to earn the money to buy a house, because when you die you are reincarnated in the form of your kids so they are entitled to it, and anyway, houses are so cheap in Britain that any poor sap who doesn’t get a house bequeathed them by Mom and Pops can work a few years to buy a house. Not.

    become a long-lived vampire to get the magic of compound interest working for you

    become a long-lived vampire to get the magic of compound interest working for you

    Compound interest works for old money, because it works very well if you have a time horizon measured in hundreds of years. Become a dynasty, or maybe become a vampire, slumbering in a box for three hundred years until your time is ready, while your Vanguard all-world index fund has been working for you for three centuries. Want to see what 200 years of compounding looks like – take a look at the Rothschilds. You can piggy-back on their investment approach, the only thing missing from the compound interest win is you need to do the whole vampire trick of taking time out while compound interest works for you. Becoming a vampire isn’t the only way, if you build a spaceship in your garage and put the hammer down once you’ve cleared Earth orbit you can slow down time for yourself while Vanguard and compounding do the heavy lifting for you. Obviously you lose your entire human web of life while doing so and won’t know any living person when you come back, but hey, that’s just the price of early retirement using compound interest. You could take your entire nuclear family with you and enjoy your winnings. Best to make sure there really is an Earth/human race/society you want to live in when you come back…

    Who else does compounding work for?

    People who have accumulated a decent wedge. Young folk always wonder why the greybeards have all the bloody money – they accumulated it over a working life. The corollary of, say, a 5% real return on income is that if you can keep your spending down to less than 5% of the capital then you won’t run out of capital. Unfortunately the only way to get that sort of return is to accept volatility which makes the spending rate indeterminate and statistical, the nominal SWR is lower than the return because the volatility means you either have to accept a variable spending rate or you will be drawing down your capital.

    That low compounding rate means you need 20 times your desired annual income even hope to achieve stasis, and as soon as you draw income the compounding will slow, or reverse. If you are spending most of your income on living the middle class dream and sending your kids to public school then you aren’t going to get anywhere – in a 20 year working life you aren’t going to accumulate 20 times your annual spend. You need to seriously earn a lot more than you currently spend, or alternatively spend a lot less than you currently earn 😉 Cutting excess spending punches above its weight, because if you want to increase what you earn keeping spending the same you start to find the taxman grabs an increasing share of what you earn, adding a headwind to your efforts.

    The forces that make compound interest are the same ones that pays rentiers and aristocrats (who are rentiers who didn’t earn their rent-seeking capital) an income. It just won’t really help you that much to retire early, if you are a typical FI/RE aspirant. I wasn’t a typical FI/RE guy, by the way – I would have been OK working to 60 if the workplace hadn’t become such a ghastly gamified bullring where form became valued over function. I have since then come to the conclusion that working to 60 would have been a terrible waste of my time, but I had to retire to find that out 😉 That would have been a working life of nearly 40 years, nearly twice the length of the one many PF writers aspire to.

    As it was I worked for one and a half times the usual target. And at the peak of my earning power I sweated three years spending at a level that the JRF classified me below the poverty line 3

    Straight between the eyes, no? You do not have enough to live on

    Straight between the eyes, no? You do not have enough to live on

    although I managed to avoid buying money at Money Shops because I didn’t spend £118 pw on Sky TV, mobile phone subscriptions and other manifestations of the Jacob trifecta of tickets, shopping and restaurants.

    This isn’t easy, guys. There is no Compound Interest Fairy that makes it easier for you. If there were, everyone would be retiring at 40. There’s an argument to be made that if we weren’t such damn fools sinking so much of our earnings into our houses then we might all be retiring earlier, but in the end it didn’t work out that way.

    Compound interest is a great story, but a myth at the same time

    It’s a fantastic story, that the passage of time gives you free money. What on earth is not to like? Waiting most of your life for that free money! That’s the bit that aristocrats get right – they had diligent ancestors who put the work in or seized the opportunities from others, depending on your point of view. If you don’t have dynastic wealth and want to retire earlier than other people, do something different from other people.  Make the difference between what you earn and what you spend bigger, and note that the taxman adds a headwind to earning more but not to spending less.

    Compound interest may help you after you retire

    Young retirees have a very long time of not working, and they need compounding to keep their capital topped up. Compound interest will do more for them after they retired, because a) they will be retired longer than when they were working, and b) they will start their retirement with a shitload of capital, unlike their impecunious Younger Self when they started saving. I could take a reasonable estimate that I have 30 (slightly optimistic) to 50 (I would be over 100) years left to live- already that would permit me to spend down some of my capital. This effect is allowed for in the Monto Carlo analyses of things like FireCalc and cFiresim. Extreme early retirees have a longer gap to bridge – a 40-year old is looking to finish work less than halfway through life, and indeed less than a third into their adult life. To a first approximation they need to live like aristocracy – aristocrats never spend their capital, they are merely the guardians of the ancestral wealth for the next generation.

    I’m a compound interest refusenik on early retirement because the maths doesn’t add up over human-sized periods of time if you come from a standing start. And I’m assuming that most wannabe early retirees are humans, and not aristocrats. You gotta get the capital before compounding will help you. It’s helping me – it has put a fair bit more money into my ISA 4 than I was allowed to put in this year. But that seed capital came from some of those 30 years of working, not the Compound Interest Fairy.


    1. you do start to see people die off in their 50s, but it isn’t terribly common
    2. compared to the 2.5 times in the previous example, the Bank of MMM would increase the capital by seven times  over 20 years. I’d bank with the Bank of MMM if I could get an account paying twice the typical real return on equities – on cash!
    3. the JRF think purely in term of income, not wealth. I entered the income I had left after saving into pension AVCs and ISAs
    4. integrated over time 2010-15
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