Savers can become ISA millionaires in under 22 years - here's everything you need to know

"It can become a reality in just over 21 years for those able to contribute the maximum allowed in an ISA each year and achieve a reasonable rate of return."

The current annual ISA allowance stands at £20,000, which translates to monthly contributions of £1,666.66 for those wishing to maximise their tax-free investment wrapper.

An investor depositing this full amount and generating seven per cent annual returns after charges would accumulate £1million within 21 years and 10 months.

However, not everyone has the capacity to invest the maximum allowance each year.

A more achievable figure for many would be £1,200 monthly, representing approximately one third of take-home pay for somebody earning £60,000 annually, with the remainder covering housing costs, bills and everyday expenses.

At this contribution level, reaching the million-pound milestone would require 25 years and nine months, assuming the same seven per cent annual return after charges.

Mr Coatsworth suggested these figures should encourage those in their thirties or early forties who are ready to take investing seriously.

A 35-year-old putting away £1,200 each month while accepting medium risk could potentially retire at 60 with a seven-figure ISA, delaying the need to access their pension. He noted, however, that inflation would reduce the purchasing power of £1million over time.

AJ Bell tested this £1,200 monthly contribution strategy across ten Investment Association sectors, beginning from January 2000. By the end of January 2026, seven of these sectors had crossed the £1million threshold.

India emerged as the standout performer, reaching the target in just 15 years and eight months by August 2016. The sector subsequently surpassed £2million after 23 years and nine months, benefiting from robust earnings growth, strong domestic consumption, enhanced corporate governance and political reforms.

China claimed second position, hitting the million-pound mark in June 2020 after 20 years and six months. North America followed in third place, achieving the goal in March 2021, propelled largely by technology sector gains.

Global funds took 24 years to reach the target, with Europe excluding the UK requiring just three additional months.

China claimed second position, hitting the million-pound mark in June 2020 after 20 years and six months. North America followed in third place, achieving the goal in March 2021, propelled largely by technology sector gains.

Global funds took 24 years to reach the target, with Europe excluding the UK requiring just three additional months.

Emerging Markets crossed the finish line in July 2025, while Japan only just made it in January 2026 after 26 years and one month.

UK equities came tantalisingly close, with investors following this strategy now holding approximately £979,746 – representing 98 per cent of the target figure.

The three sectors yet to reach £1million all have significant bond exposure. Mixed Investment funds with 40-85 per cent equity allocation have accumulated roughly £900,000, whilst the more cautious 20-60 per cent category sits at around 70 per cent of the goal.

This disparity reflects bonds' traditionally lower returns compared to shares. Nevertheless, Mr Coatsworth emphasised that mixed investment portfolios remain appropriate for many investors, providing valuable diversification.

Predicting which sectors would outperform at the turn of the millennium would have proved extremely difficult, making a balanced approach sensible for avoiding concentrated risk.

Mr Coatsworth stressed that few investors would realistically concentrate their entire ISA in a single sector. Exceptions might include global funds offering broad worldwide exposure or multi-asset products, though some may feel comfortable backing the US given its historical performance.

The majority of savers will instead adopt a diversified approach, spreading their investments across different regions and asset classes. "Diversification is an investor's best friend as you never know when one part of your portfolio will need propping up by another bit," he said.

Ultimately, the most crucial factor remains steadfastness. "The key ingredient to investment success is consistency. Form a plan, don't miss a monthly payment into your ISA, and stick with it through good and bad times," Mr Coatsworth advised, likening the discipline required to maintaining healthy eating and regular exercise habits.