Answers · UK 2025/26
How long does it take to save £100,000 in an ISA paying £500 a month?
About 12 to 13 years at a 5% annual return. Paying £500 a month (£6,000 a year, within the £20,000 ISA allowance) at 5% compound growth reaches roughly £100,000 in around 12.5 years. At 7% it takes about 11 years; at 3% closer to 15 years.
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Saving £500 a month inside a stocks and shares ISA stays comfortably within the £20,000 annual ISA allowance, and all growth is free of UK tax. The time to reach £100,000 depends heavily on the return. With monthly contributions of £500 and a 5% annual return compounded monthly, the pot passes £100,000 after roughly 12.5 years, by which point you will have paid in about £75,000 and earned around £25,000 in tax-free growth. At a 7% return the same £500 a month reaches £100,000 in about 11 years; at a cautious 3% it takes closer to 15 years. Worked example: after 10 years at 5%, £500 a month is worth about £77,600 from £60,000 of contributions. The extra two to three years to hit £100,000 shows how compounding accelerates as the balance grows. Because the money is in an ISA, you pay no Income Tax on interest, no Dividend Tax, and no Capital Gains Tax, so the headline return is also the net return. Outside an ISA, higher-rate savers could lose 40% of interest above the £500 Personal Savings Allowance, and Dividend Tax of 35.75% above the £500 dividend allowance. Use the ISA calculator and the compound interest calculator to test different monthly amounts and return rates. Past returns are not a guarantee; for ISA rules see gov.uk.
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This answer is informational only and does not constitute financial, tax or legal advice. Figures are for the 2025/26 UK tax year. See our methodology and sources.