This Individual Savings Account (ISA) Calculator helps you see how your savings and investments can grow tax-free in the UK. Whether you’re using a Cash ISA, Stocks & Shares ISA, or Lifetime ISA, this tool can help you plan for your financial goals and make the most of your annual allowance.
How This Individual Savings Account (ISA) Calculator Works
Our calculator is designed to be simple and flexible. It lets you experiment with different scenarios to see how your ISA could grow over time.
- Enter your starting investment amount.
- Add any regular contributions (monthly or yearly).
- Choose your investment period (number of years).
- Select an estimated interest or growth rate.
You’ll instantly see:
- Your total contributions
- The total interest or investment growth earned
- The final balance at the end of your chosen period
- A year-by-year breakdown of your ISA’s growth
What Is an ISA?
An Individual Savings Account (ISA) is a special type of savings or investment account available to UK residents. The main benefit is that any interest, dividends, or capital gains you earn within an ISA are completely tax-free.
There are several types of ISAs, each with its own rules and benefits:
- Cash ISA: Works like a regular savings account, but with tax-free interest.
- Stocks & Shares ISA: Lets you invest in shares, funds, and bonds, with all returns sheltered from tax.
- Lifetime ISA (LISA): Designed for first-time home buyers or retirement savings, with a government bonus.
- Innovative Finance ISA: For peer-to-peer lending and crowdfunding investments.
- Junior ISA: For saving on behalf of children under 18.
ISA Allowance and Limits
Each tax year, there’s a maximum amount you can put into ISAs (the “ISA allowance”). For the 2025/26 tax year, the allowance is £20,000 per adult.
- You can split your allowance across different types of ISAs, but the total can’t exceed the annual limit.
- Lifetime ISAs have a separate annual limit of £4,000 (which counts towards your overall ISA allowance).
- Junior ISAs have their own annual limit (currently £9,000).
Example: How Your ISA Can Grow
Let’s say you invest £5,000 in a Stocks & Shares ISA and add £200 per month for 10 years, with an average annual growth rate of 5%:
| Year | Total Contributions | Interest/Growth Earned | ISA Balance |
|---|---|---|---|
| 1 | £7,400 | £185 | £7,585 |
| 5 | £17,000 | £2,200 | £19,200 |
| 10 | £29,000 | £8,100 | £37,100 |
This example shows how regular contributions and compounding growth can help your ISA balance grow significantly over time.
Why Use an ISA?
ISAs are one of the most tax-efficient and flexible ways to save and invest in the UK. By sheltering your savings and investments from income tax, dividend tax, and capital gains tax, ISAs allow your money to grow faster than it would in a standard account. Whether you’re building an emergency fund, saving for a home, or investing for retirement, using an ISA can help you reach your goals sooner and with less tax drag. The wide range of ISA types means there’s an option for nearly every saver or investor, regardless of risk tolerance or time horizon.
Opening an ISA means you can:
- Grow your savings or investments without paying tax on interest, dividends, or capital gains.
- Access a wide range of savings and investment options.
- Use your annual allowance to maximize your tax-free returns.
- Save for specific goals, like buying a home or retirement, with special ISAs like the LISA.
Tips for Maximizing Your ISA
To get the most benefit from your ISA, it’s important to have a strategy. Making the most of your annual allowance, choosing the right type of ISA for your needs, and contributing regularly can all make a big difference over time. Even small, consistent actions can add up to significant tax-free growth. Here are some practical tips to help you maximize your ISA’s potential:
- Start early in the tax year to maximize your time in the market.
- Make regular contributions, even if they’re small.
- Review your ISA options each year—Cash ISAs are safer, but Stocks & Shares ISAs may offer higher long-term growth.
- Don’t forget to use your full allowance if you can—it’s “use it or lose it” each tax year.
- Consider a Lifetime ISA if you’re saving for your first home or retirement.
Frequently Asked Questions
Can I withdraw money from my ISA at any time?
Yes, but some ISAs (like Lifetime ISAs) have penalties for early withdrawal unless it’s for a first home or retirement.
Can I transfer my ISA to another provider?
Yes, you can transfer your ISA to get a better rate or different investment options. Always use the official transfer process to keep your tax benefits.
What happens if I exceed the ISA allowance?
Any excess contributions won’t be tax-free and may be returned to you by your provider.
Are ISAs safe?
Cash ISAs are protected by the FSCS up to £85,000 per provider. Stocks & Shares ISAs carry investment risk, so your balance can go up or down.