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How much should you invest in your ISA?

Contrary to popular belief, investing can be hassle-free. Instead of being overwhelmed by the different strategies and perceived complexity of the financial markets, you can maximise your returns just by setting up a simple direct debit to your well chosen ISA.

At a time when society is increasingly time-poor, managing your finances can be pushed to the bottom of your to-do list due to the misconception that you need a large lump sum to start investing, and the expertise to time your movements in the market perfectly.

Instead, regular investing can be an easy way to grow your money more efficiently, especially if you’re making the most of your ISA allowance.

Why make the most of your full allowance?

Every year, savers are allowed a maximum ISA allowance that you can save within the tax-free wrapper during the tax year period (April to April). For the 2020/21 tax year, the maximum ISA allowance is set at £20,000, which can be split across cash and stocks and shares ISAs provided the combination does not exceed the limit. 

Importantly, any unused allowance does not roll over to the following tax year, meaning it is lost forever if the maximum amount is not filled. For anyone with the means, who is looking to save as much as possible for their future, it is important to be aware of the deadline to ensure you’re getting the most out of your ISA portfolio now and in the future. 

Putting in more, earlier in the life cycle of your investments, sets you up for greater potential gains down the line as these funds begin to work for you. To fully utilise your tax-free ISA allowance for the 20/21 tax year, make all contributions before the 5th April deadline next year. 

The benefits of regular investing

Regular investment plans can take a lot of the hassle out of investing. You don’t need to decide when to invest and you don’t need to time the market. All you need to decide is how much you want to invest.

Not only is regular investing simple, but it can actually have financial benefits over time. By averaging out the price of an asset, you can lower the total amount you pay for it during periods of volatility – this is called pound cost averaging and we explain it in more detail below. 

There’s another simple way to grow your money; maximising your ISA allowance. You can invest up to £20,000 in your ISA each year, and any growth in the value of your money and any income can build up tax-free.

By protecting your money in a tax-efficient wrapper, you can keep all of your profit without handing more than you need to the taxman.

Regular investment plans for your ISA

If you’re looking to secure your financial future for the long-term, we’ve developed three regular investment plans that are popular with investors looking to make the most of their ISA allowance. Of course, the ISA allowance could change in the future, the government could increase or decrease it in line with policies that impact savers. That makes starting sooner rather than later all the more important.

Below, we’ve outlined what you could have by investing in one of these regular investment plans for 30 years. This is a long-term investment, but the benefits are clear to see.

We’ve assumed you will have invested in a balanced, diversified portfolio with 60% exposure to equities and 40% exposure to bonds.

If you’d started out invested in this 60/40 model portfolio in 1990 and continued to today, your money would have grown by an annualised 7.49%. We’ve assumed this rate of growth for our regular savings plans below, along with a more conservative 5% growth estimate.

Investing £400 a month

  • How much you’ll have with 7.49% annualised growth: £422,000
  • How much you’ll have with 5% annualised growth: £272,000

By earmarking £400 to your ISA each month, you can grow your ISA to be worth around £422,000 tax-free. This could be used to help your grandchildren get on the property ladder, fund your dream sabbatical, or provide a useful extra income throughout retirement.

It’s important you understand exactly how much you’re paying in fees before you start investing, as unnecessarily expensive charges can eat into your return. In the calculations below, we factor in the impact of a 1% fee on your return, paid on a quarterly basis.

Moneyfarm’s fee structure is such that the more you invest with us, the less of a percentage you’ll pay in fees.

Investing £800 a month

  • How much you’ll have with 7.49% annualised growth: £843,000
  • How much you’ll have with 5% annualised growth: £545,000

To invest half of your ISA allowance each year, our £800 a month regular savings plan will do the trick.

ISAs are flexible, which gives you control over when you want to withdraw from your ISA in case of an emergency. Yet time has the power to significantly influence your returns. The longer you can invest, the more you can expect your investments to grow – although the value of your money can also fall.


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By investing £800 a month for 30 years, you could have nearly £850,000, which will help secure your family’s financial future.

Investing £1,600 a month

  • How much you’ll have with 7.49% annualised growth: £1.7 million
  • How much you’ll have with 5% annualised growth: £1.1 million

To make the most of your full £20,000 ISA allowance, you should look to invest £1,600 a month. This will take your annual deposit to £19,200, leaving you with an extra £800 of your allowance to play with.

You may want to keep this in a cash ISA to top-up your cash savings. It’s important you keep at least three months of outgoings in an easily accessible savings account. This £800 won’t be enough on its own, but at least you can keep any return you get on your savings account protected from tax.

This could be a useful addition to your pension income, as there are tax charges if you contribute over your annual allowance, which is currently £1,055,000.

Tax benefits of an ISA

ISAs are a simple way to grow your money in a tax-efficient manner. You can invest up to £20,000 in your ISA each year, and you can watch your money grow within your tax-free wrapper, including any income you build up.

This can make a real difference over the long-term and can be a powerful tool to help you reach your financial goals.

There are a number of different ISA options available to help you protect your money, but the two main ones are cash ISAs and stocks and shares ISAs. Both play an important part in financial planning and here you can find an accurate study of their performance over a ten-year period.

Cash ISAs are great for savers with a short time horizon and those who want to take a limited risk with their money. But if you want to grow your money for the future, you can look to offset the impact of inflation on your savings with a stocks and shares ISA.

Stocks and shares ISAs allow you to invest in the financial markets, protecting growth in the value of your investments and any income from the taxman.

The ISA allowance

You can invest up to £20,000 into one ISA each year, or split your allowance between a stocks and shares ISA, cash ISA, Lifetime ISA (LISA), and Innovative Finance ISA.

As it’s an individual allowance, partners can invest up to £40,000 each year to benefit from the generous tax incentives.

You don’t have to use all of your £20,000 ISA allowance, just what you’re comfortable with. But, as you can’t roll it into the next tax year, it’s worth remembering you either use it or lose it.

Four tips to maximise your investments

Once you’ve set up your ISA, follow these four simple tips to make your money go further and help you reach your financial goals.


Time really is your friend when it comes to investing for the future. Not only does it allow you to ride out short-term fluctuations in favour of long-term growth, but it also allows you to take on more risk with your money. The more risk you take, the more your money can grow – although your investments also have further to fall. When investing for your retirement, for example, time is a crucial factor.

Impact of fees

Remember that fees eat into your returns. Fees are a fact of life, but it’s important you understand exactly what you’re paying before you choose a provider. Expensive fees don’t always generate the returns they promise and make it harder for investors to make a profit. At Moneyfarm, we’ll never charge you over 1.04% all-in, allowing you to keep more of your money and make it go further.


There’s always a risk to investing, even keeping it in cash exposes you to the impact of inflation. Instead, you can manage the risk in your portfolio through diversification. By spreading your money across different investments, asset classes and geographies, you hope to offset any losses with gains made elsewhere in your portfolio.

Diversification can be expensive to get right, which is why exchange-traded funds are becoming increasingly popular with investors wanting low-cost diversification.

Pound cost averaging

Another way to maximise your returns is to adopt a regular investing habit. When you invest, you want to buy an asset at a low price and sell it at a high price. It’s very difficult to time the market – even the professionals struggle – and this can weigh on your returns.

Luckily there’s an easy way to make your money go further. By investing regularly, you can smooth out the price you pay for an asset over time. This can lower the amount you pay for your investments during turbulent periods, maximising your returns.

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As with all investing, your capital is at risk. The value of your portfolio with Moneyfarm can go down as well as up and you may get back less than you invest.