Ever imagined having an extra £1,000 a week by way of a second income? With the tax benefits of the Stocks and Shares ISA, and the long-term power of the stock market, it doesn’t have to be a pipe dream.

Sure, it’ll take some time at the beginning to set up your portfolio. But with the right investment strategy and a little maintenance, investing in an ISA can be a powerful engine for building long-term passive income.

A £1k a week works out at £52,000 a year. Here’s how you could put yourself firmly on track to hitting that magical target.

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 ISA wealth

Brits can put up to £20,000 a year into a Stocks and Shares ISA. With patience, and an eventual rotation into high-yield dividend shares, that could be more than enough for a serious second income.

Let’s crunch the numbers and I’ll show you how. Over the last decade, the average annual return on an investing ISA is 9.64%. There’s been some ups and downs in that time, but the long-term direction of stock markets has been firmly up.

So, what about if someone drip-fed £600 a month into their ISA, and managed to match that 9.64% figure? After 25 years they’d have £748,925 sitting in their account, thanks also to the beauty of compound returns.

If this was then invested in 7%-yielding dividend shares, our investor would enjoy an annual passive income of £52,425, or £1,008 a week.

A top FTSE income stock

Past performance isn’t always a reliable guide to future returns. And that 9.64% annual return will require some careful stock selection to make a reality. We’re talking about, for instance, a mix of shares spanning different industries and regions to spread risk and capture a range of investment opportunities.

Building a portfolio of complementary shares is also key to generating strong returns. Growth shares can boost ISA growth during good times; dividend shares provide an income and a solid return when times are tough; and value shares can deliver strong capital gains and protect against volatility.

M&G (LSE:MNG) is a great share to consider for portfolio growth and eventually drawing an ISA income. Dividend yields have consistently ranged between 6% and 9% since it entered the FTSE 100 in 2019. For this year, its yield sits bang on 7%.

So what makes it such a top dividend share? From its asset management and insurance divisions, it generates boatloads of cash it can then distribute to shareholders. M&G’s goal is to “maintain a progressive and sustainable dividend policy“, and with a strong balance sheet it’s in great shape to keep delivering. Its Solvency II capital ratio is 242%, sailing above the 100% regulators require.

The FTSE firm does face intense competition across its product lines. This in turn poses a risk to profits and dividends. But I believe M&G’s leading position in growing markets should keep delivering the goods.

A dip buying opportunity?

Long-term investors can also boost their chances of hitting that 9.64% return by buying shares cheaply. Following recent stock market volatility, I think now’s a great time to go looking for bargains that could recover strongly over time.