We have some exciting news to share! The Motley Fool UK has now become The Twelfth Magpie -- an independent, UK-owned company, led by our long-serving UK management team — Mark Rogers, Chris Nials and Heather Adlington. In practical terms, it’s the same team you know, now fully focused on serving our UK readers and members.

Just as importantly, our approach remains unchanged: long-term, jargon-free, and on your side. This site is our new home, and there will be extra tweaks made across the coming few days as we settle in. So if anything looks a little off, please bear with us!

The content of this article was relevant at the time of publishing. Circumstances change continuously and caution should therefore be exercised when relying upon any content contained within this article.

Turning an empty ISA into £20,185 of yearly extra income… in just 15 years

We’d all love an extra income, whether it’s for retirement or to top up our earnings. Dr James Fox explains how to do it when starting with nothing.

Close-up of British bank notes

Image source: Getty Images

You’re reading a free article with opinions that may differ from The Motley Fool’s Premium Investing Services. Become a Motley Fool member today to get instant access to our top analyst recommendations, in-depth research, investing resources, and more. Learn More.

I’m sure many of us have had the thought: “If only I had some extra income to make life a little bit easier or more enjoyable.

Well, it’s certainly possible. It just requires time, effort, and plenty of commitment.

XXX

Time

Time is one of the most crucial factors when trying to harness the power of compound returns. The longer my investment continues in the market, the more time it has to benefit from compounding. This occurs as my investment generates returns. And those returns, in turn, generate more returns.

Over time, this compounding effect can significantly impact my investment’s growth and potential for even larger returns. As such, starting early and giving my investments time to compound can have a substantial impact my portfolio overall growth.

Billionaire investor Warren Buffett is the perfect illustration of this. Yes, he’s invested well, but as he says, he’s a beneficiary of good genes, being American… and compound returns. This is because a compound returns strategy leads to exponential growth and, at 92, his investments have had plenty of time to compound.

This is why many parents will start a fund for their children before they’re even born. Allowing £100 a month — the size of a child benefit in the UK — to compound over 20 years with a 10% annualised return would create a portfolio worth over £75,000.

Committed investment

However, what if we’re later in life and we’re looking to create a second income to supplement our pension or late-career income? Well, we may be looking at a shorter timespan, and therefore there’s less opportunity for time to do its thing. But it’s still possible to turning nothing into a sizeable income-generating portfolio.

Firstly, I’m going to want to use my Stocks and Shares ISA. That’s because the wrapper gives me the ability to earn tax-free dividends — capital gains are free of tax too. This is hugely beneficial when I’m targeting passive income.

Please note that tax treatment depends on the individual circumstances of each client and may be subject to change in future. The content in this article is provided for information purposes only. It is not intended to be, neither does it constitute, any form of tax advice. Readers are responsible for carrying out their own due diligence and for obtaining professional advice before making any investment decisions.

Monthly contributions are key when starting with nothing. Obviously, we need to build our portfolio, and there’s nothing better than disciplined and scheduled saving — ideally through automated saving. It also allows us to benefit from pound-cost-averaging.

How it works

If we’re working with a 15-year timeframe, we may need to contribute more, and continually increase that contribution. Here, I’ve assumed a monthly contribution of £400, while increasing the size of that contribution by 5% annually (keeping up with inflation or personal salary growth).

The other variable is annualised portfolio growth. Of course, this varies hugely depending on the quality of the stocks I chose — if I pick poorly, I could lose money. This is why it’s very important that I research my stocks well.

In this calculation below, I’m assumed a strong 10% annualised returns.

Portfolio sizeExtra income generation
5 years£33,900.74£2,909.26
10 years£99,044.06£9,000.01
15 years£218,179.34£20,185.31

James Fox has no position in any of the shares mentioned. The Motley Fool UK has no position in any of the shares mentioned. Views expressed on the companies mentioned in this article are those of the writer and therefore may differ from the official recommendations we make in our subscription services such as Share Advisor, Hidden Winners and Pro. Here at The Motley Fool we believe that considering a diverse range of insights makes us better investors.

More on Investing Articles

Friends and sisters exploring the outdoors together in Cornwall. They are standing with their arms around each other at the coast.
Investing Articles

£503 buys 14 shares in this FTSE 250 stock that returned 23.9% annually for the last 15 years

This FTSE 250 stock has averaged a huge return for 15 years. At today's price, £503 buys 14 shares. But…

Read more »

Black woman using loudspeaker to be heard
Investing Articles

£1,000 buys 25 shares in this FTSE 100 stock that’s returned 29.2% annually for the last 10 years

This FTSE 100 mining stock has returned close to 30% a year for a decade. At 3,995p, £1,000 buys 25…

Read more »

Female student sitting at the steps and using laptop
Investing Articles

Down 47%, is this growth stock finally worth buying in May?

With a £288m order book and a hidden pipeline of defence and nuclear contracts, is this growth stock now too…

Read more »

House models and one with REIT - standing for real estate investment trust - written on it.
Investing Articles

2 REITs yielding 7%+ to consider for passive income in 2026

A REIT backed by the NHS and another backed by Tesco and Sainsbury's with both yielding 7%+. Here's why I'm…

Read more »

Woman riding her old fashioned bicycle along the Beach Esplanade at Aberdeen, Scotland.
Investing Articles

Just 97 shares of this UK dividend stock generate £238 in passive income

A 5.7% yield, £238 in passive income from just 97 shares, and one of the most divisive dividend stocks on…

Read more »

ISA coins
Investing Articles

£10,000 in an ISA generates a second income of…

The London Stock Exchange is home to some of the world's most generous dividends. But how big a second income…

Read more »

Shot of a senior man drinking coffee and looking thoughtfully out of a window
Investing Articles

Expert recommendations: 2 top income stocks yielding 7%+!

With yields of 7.2% and 7.8% respectively, these two income stocks are catching the eyes of institutional analysts. Should investors…

Read more »

Illustration of flames over a black background
Investing Articles

3 top income-focused stocks to buy in May 2026, according to experts

Looking for a stock to buy for income in May 2026? Experts have flagged these three UK dividend shares as…

Read more »