Pocket money into KiwiSaver – how to maximise compound interest

Date Published: 16 August 2022

Could parents use KiwiSaver as a method for rewarding children in the form of pocket money?  Read on to see how one of our clients is successfully doing it and teaching their children about the magic of compound interest.

Compound Interest

Whether Albert Einstein ever actually said that compounding interest is the eighth wonder of the world is debatable.  Regardless, the sentiment grows increasingly more and more accurate every day (see what I did there).

Compound interest is the effect of invested money receiving regular interest payments that are reinvested and allowed to grow.

For a simple example, let’s look at $100 invested at 10% per annum (a high-interest rate but easy to calculate).

Day 1 – $100
1 year – $110
2 years – $121
5 years – $161
20 years – $739

So an investment of $100 has increased to over $700 in 20 years and will increase by another $73 the next year.  We are almost at the point where we are doubling our initial investment every year, all thanks to compound interest.  If you had simply left in the $100 and taken out the interest, you would have received $200 of interest and still only have your original $100.

Saving for young children

It shouldn’t come as a surprise that putting money aside for young children will result in huge returns for their retirement.  Let’s look at an example of $1,000 savings put into an investment fund for a newborn.

Let’s assume the savings will average a 10% return on this fund but let’s take off 2% to allow for tax.  So an 8% net return over 65 years would mean a total savings of $178,000 upon retirement.  While this isn’t enough to retire, it shows how $1,000 can change into a much larger amount given enough time.

There are 2 things to acknowledge here.

Don’t put it off

Leaving it until later in your child’s life significantly reduces the amount saved.  $1,000 given to a 20 year old – as opposed to a newborn – will mean ~$36,00 in the fund at retirement instead of $178,000.

Regular small deposits can massively increase the end result.

Even a small regular deposit will grow your child’s retirement savings if you can afford it.  This is all thanks, again, to compound interest.  Remember the initial deposit of $1,000, which became $178,000 at retirement.  Well, if we add another $20 per week onto that for 65 years, you have deposited a total of $63,400 into the fund however, that fund has grown to $2,318,000 (based on the same 8% average growth).  At this stage, we’re talking serious money to retire on.

Pocket money, KiwiSaver and compound interest

So, if you use pocket money to facilitate family-based child slavery, consider putting some of that money into KiwiSaver.  Notice I say some of it.  Children don’t wash dishes on the promise of a leisurely retirement in 50 years’ time.  You’ll probably need to give your child some actual money too.

But it’s an excellent opportunity to teach your children about interest.  For this article, I have been using this compound interest calculator.  Feel free to play with it. Here’s an example that might encourage the savings bug.

Let’s say your 10-year-old child has $5,000 in their savings.  You’re putting $20 into that fund per week (in the calculator, I put $80 per month).  The calculator shows a total of $1,358,934 at retirement in 55 years.  What does it show if they deposit one $20 note into that fund?  Not multiple, just one note.  The answer is $1,360,540.  A difference of $1,606.  $20 put into their fund today gives them $1,606 at retirement!


I know that pocket money put into a savings account or KiwiSaver will not thrill most children.  I can hear parents screaming at the screen right now.  But I do suggest taking the opportunity to show them what a little savings can mean for their retirement.  The calculations haven’t considered purchasing houses in their early adult life and all other life events affecting their savings.  The bottom line is, however, that the sooner you can start putting money aside for your child’s retirement, the easier it will be for them.  All thanks to the magic of compound interest.

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