For a full-time worker in their 50s, building a passive income stream before retirement might be easier than first thought. In fact, a £18,472 investment portfolio generating a 6% yield could produce around £1,108 a year in extra cash. Better still, if those dividends are reinvested over time, the income could grow significantly.

But how realistic is that opportunity?

Let’s crunch some numbers. That £1,108 could buy more shares to add to the total pot. Each of these new shares also pay a dividend. So by the end of year two, it could result in a total pot worth £19,580 generating £1,175 of dividends. That’s an extra £67 of passive cash.

It might not seem like much now, but over time those additional payments can add up.

Let’s take things a step further. Many dividend shares also manage to grow payments over time. Dividend growth can amplify passive income even further.

Several top FTSE 100 income shares have grown dividends by 8% a year. This causes a snowball effect over time. For instance, with an initial 6% yield, 8% dividend growth rate, and dividend reinvestment, I calculate that our investor could expect to earn £8,256 in annual passive income. That equates to a whopping 45% yield on initial cost.

Of course, in reality, things can change over time. Dividends can rise or fall depending on market factors.

That’s why I focus on solid and stable shares that are most likely to remain consistent over time.

Does Legal & General deserve a closer look?

Enter Legal and General (LSE:LGEN). This stock frequently appears on the radar of UK income investors. The company operates across pensions, retirement products, and asset management. These businesses generate substantial cash flows that have historically supported attractive shareholder payouts.

Also, the UK’s ageing population continues to increase demand for retirement planning. This should provide a favourable backdrop for growth in the years ahead.

While no stock is perfect, Legal & General’s blend of cash generation, established market position, and dividend history helps explain why income investors continue to pay attention.

Currently, this income share offers an 8% dividend yield. It has also managed to grow dividends by 5% a year over the past decade. This looks like an appealing option.

But investors should never solely focus on yield. A high yield is only valuable if it can be sustained. Also bear in mind that Legal & General isn’t immune to weaker economic growth. It’s also impacted by changes to pension regulations and all these factors can put pressure on future dividend payments.

Is now the right time to build passive income?

Many workers in their 50s feel they’ve missed their opportunity to build meaningful wealth. I think that’s often a mistake.

Even with retirement approaching, 10 to 12 years could be enough time for compounding to make a significant difference, especially when dividends are reinvested.

In my view, the most important step isn’t finding the perfect dividend share. It’s building a portfolio of quality businesses and giving them time to work.

And if Legal & General doesn’t float your boat, there are plenty more fish in the Footsie.

Should you invest £5,000 in Legal & General Group Plc right now?

When investing expert Mark Rogers and his team have a stock tip, it can pay to listen. After all, the flagship Twelfth Magpie Share Advisor newsletter he has run for nearly a decade has provided thousands of paying members with top stock recommendations from the UK and US markets.

And right now, Mark thinks there are 6 standout stocks that investors should consider buying. Want to see if Legal & General Group Plc made the list?

Harshil Patel does not hold any positions in the companies mentioned.