We’re now well into the new 2026/27 tax season, so Stocks and Shares ISA investors should be thinking about their annual allowance.

A new year means a fresh £20k contribution allowance for tax-free investment into a wide range of assets, including stocks, bonds, and commodities.

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.

When building towards a passive income stream, this tax relief can make a huge difference.

But don’t take my word for it — check out these calculations.

The road to £10k a year

Whether aiming for returns from growth or income, bringing in £10,000 a year will require a significant investment.

You won’t be able to achieve it in just one year, but rather grow towards it through compounding. This means regular contributions and reinvested dividends.

For example:

• Start with a £20k lump sum.
• Invest a further £300 per month.
• Aim for an average yield of 6%.
• Assume average capital growth of 4%.

Based on my calculations, that ISA could grow to £171,270 within 15 years. Assuming the average yield held, it would pay out £10,276 a year.

By boosting the annual contributions to £500 a month, you could slash four years off that timeline.

Of course, these are just projections based on historical market averages. They’re neither a best-case scenario nor worst, but the actual result could vary wildly.

So how can we better ensure reliable, regular returns?

The low-risk, reliable portfolio

One thing’s for sure: when aiming for long-term, stable income, it’s best to play it safe. This means avoiding speculative growth stocks, overblown hype stories, and short-term gains.

Rather, focus on steady returns from defensive shares with long and established dividend track records.

An easy way to spot these shares? Just think of the most boring company you know — for example, National Grid (LSE: NG.).

Here’s why…

Predictable returns

As the UK’s largest utility company, it keeps the lights on and the gas flowing. That’s a pretty critical and high-demand service, but it’s not exactly exciting.

Exciting can be fun but it usually means volatility and unreliability — the opposite of what we’re looking for.

National Grid’s earnings come from regulated assets, meaning returns are set by regulators. That makes revenues stable and relatively predictable, even during economic downturns.

It pays a realistic, well-covered dividend that often results in a lower yield (3%-5%). But it reduces the chance of having to pause payments, which it hasn’t done for 31 years.

Recently, it has invested heavily into a green energy transition, upgrading the grid for renewables like wind and solar. That forced a 13.69% dividend reduction.

Ideally, the move should help reduce costs in the long run but there’s a always a risk it doesn’t pay off. If regulatory changes hit profits, it may have to cut dividends further.

The bottom line

When investing with a 10-20 year outlook, focusing on reliable companies usually works out better than betting on the latest fad.

Aside from utilities like National Grid, which is worth considering, retail and healthcare stocks are also good options. Think GSK, Tesco, or Unilever.

But don’t be too careful — a few growth stocks like 3i Group or Diploma can also be helpful to get the momentum going. And that’s just a few of the options I’ve explored lately…