How to target a £100,000 portfolio in a Stocks and Shares ISA

Investing with a Stocks and Shares ISA is one of the best ways for British investors to build wealth, in my opinion. And following the recent cuts to dividend and capital gains allowances, the tax benefits of this account are making it even more valuable.

Investors are restricted to only injecting £20,000 per year into their ISA. But this is more than enough capital to build an investment portfolio in the six-figure territory. And relatively speaking, it won’t even take that long, especially if an individual can max out their allowance each year.

Stocks and Shares ISA benefits

Let’s say an investor earns £5,000 in dividends a year. If they’re in the basic rate tax band, they’re exposed to 8.75% tax beyond the first £1,000. That’s £350 going to the tax man. And the situation becomes diabolical for anyone fortunate (or unfortunate) to be in the higher rate tax band since the dividend tax surges to 33.75% or £1,350!

To add insult to injury, the £1,000 tax-free dividend allowance is being cut in half as of April 2024. But the good news is that this capital outflow can be eliminated entirely with a Stocks and Shares ISA. Any capital gains or dividends received in this tax-efficient account are immune to such taxes. And investors don’t even need to declare it on their annual tax return.

Let’s demonstrate how valuable this advantage is. £1,350 compounded over 30 years at the stock market’s average return of 10% is equal to £26,780.49. In other words, those earning £5,000 in dividends outside an ISA today are missing out on almost £27k in long-term wealth. And that doesn’t even account for any returns from capital gains.

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.

Building a £100k portfolio

Given the positive impact of tax-free investment gains, investors should strive to maximise their annual ISA allowance as much as possible. After all, the allowance doesn’t roll over, and any allocation not used within a tax year is lost forever.

Assuming an investor is successful in this pursuit, this translates into investing roughly £1,667 each month. And by investing in a low-cost index fund, matching the stock market’s average return is relatively easy, resulting in a six-figure portfolio within just four years.

Of course, putting aside £1,667 each month for investing is pretty difficult for most households. In fact, data from HMRC shows that the majority of Stocks and Shares ISA holders fail to even come close to this. But that doesn’t mean it’s not possible to reach £100k.

Even if an investor can only comfortably allocate £500 each month, they’ll still be able to reach their milestone within 10 years. And by deploying stock-picking strategies to boost investment returns, the waiting time can be significantly reduced.

Of course, there are never any guarantees when it comes to investing. Just because indices like the FTSE 250 or S&P 500 have delivered around 10% annualised returns in the past doesn’t mean they will continue to do so in the future.

And while stock picking paves the way to market-beating returns, it can also decimate wealth when executed poorly. Nevertheless, when following a disciplined investment strategy within a Stocks and Shares ISA, British investors can position themselves to be far better off in the long run. At least, that’s what experience has taught me.