Jasmine Birtles
Your money-making expert. Financial journalist, TV and radio personality.
I Found The Best Flexible ISA for Stock Market Investors!
Ruby Layram
6th Mar 2025
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Investing into a stocks and shares ISA is a cheat sheet for tax-free returns. In the UK, you can invest up to £20,000 per year into the stock market, through an ISA, and pay £0 to the tax man!
However, many stocks and shares ISAs come with rigid withdrawal guidelines which make it tricky to withdraw and deposit funds as and when you wish. This can be frustrating for investors who want to be able to dip in and out of their portfolio, without affecting their ISA allowance.
I’ve done a bit of digging and found the best flexible stocks and shares ISA on the market! This ISA allows you to invest, withdraw and move your funds around, without it affecting your yearly allowance.
In this post, I will explain which ISA it is (because I know you’re all wondering!), how flexible ISAs work and how you can get started today.
IG Stocks and Shares ISA: The Best Flexible ISA for 2025
At MoneyMagpie, we don’t agree with gatekeeping (especially when we come across something as exciting as this!). So, without further ado, the best flexible stocks and shares ISA that I have found is the IG Stocks and Shares ISA.
Get started with the IG Stocks and Shares ISA here.
The main draw of this stocks and shares ISA is the fact that you can withdraw from your account, without it affecting your ISA allowance. This is appealing to investors who want to be able to dip into their pot and access their cash as and when they want to.
If the thought of locking your money away has put you off from investing in the stock market, this could be the solution for you!
It’s also worth noting that IG is currently offering a cashback offer, available to new UK customers who open a Stocks and Shares ISA between 4 March – 30 April 2025.
Eligible customers will receive 1% cashback on net deposits (deposits minus withdrawals) made during the current tax year, up to a maximum of £200. Cashback will be paid after 5 April 2026 into a general investing account (not the ISA due to tax rules).
To qualify, you must make at least one trade between 4 March 2025 – 5 April 2026.
Buy and sell US shares commission-free!
Flexibility isn’t the only reason that this stocks and shares ISA stood out to me. IG also offers some of the lowest trading fees on the market. You can buy US shares with zero commissions and UK shares from just £3 per trade. This transparency will make it a lot easier to keep track of the fees involved with using a stocks and shares ISA to invest.
Investors can choose from an extensive range of 13,000 shares and funds or opt for a more hands-off approach by investing in an expertly managed portfolio. If you’re familiar with IG, you will already know that the trading platform provides an excellent range of tools for research and analysis, helping every investor to make smart decisions.
A provider that you can trust
When it comes to putting your money on the line, security and reliability is key. I was impressed to find that IG is an FTSE 250 registered company, offers 24/7 customer support and was recently a recipient of the Best Stocks and Shares ISA Provider 2024 award from Online Personal Wealth Awards.
In fact, the trading platform has received a library of awards from various awards bodies. These awards are a clear indicator that a platform can be trusted – reputation says everything!
What Exactly Is a Flexible ISA?
A flexible ISA lets you withdraw money and put it back in the same tax year without it affecting your allowance.
For example, if the annual ISA limit is £20,000 and you’ve deposited £15,000, you’d normally only be able to add another £5,000. But if you then withdraw £10,000, a standard ISA would still cap you at £5,000 more for the year.
With a flexible ISA, you could re-deposit the £10,000 you took out and still add the extra £5,000, giving you more freedom to move your money around.
Just keep in mind that not all ISA providers offer flexible ISAs, so it’s worth checking before you open one!
How to Find the Best Flexible ISA for You
Although IG stood out to me as the best flexible ISA, it’s important to do your own research and shop around to find an option that is best suited to your needs.
Here’s how to understand whether an ISA is worth considering:
1. Flexibility – Is it truly flexible?
Not all ISAs that claim to be “flexible” actually are. Some providers only allow flexibility for cash withdrawals, not investments.
- Check the provider’s terms—does it specifically state that it’s a “Flexible ISA”?
- Look at replacement rules—can you only replace withdrawn cash, or does it cover stocks and funds too?
- How quickly can you withdraw and replace funds? Some platforms take days to process transactions, which could impact your investment strategy.
- Investment options – What can you invest in?
Different providers offer different investment choices. If you have a particular strategy in mind, make sure your provider supports it. To build a diverse portfolio, look for providers that offer:
- Stocks – Can you buy individual shares, and if so, which markets are available?
- Funds & ETFs – Are there a variety of managed funds, index funds, and ETFs?
- Bonds & Other Assets – Can you invest in government bonds, corporate bonds, or alternative assets?
- Ready-made vs DIY portfolios – Some providers offer robo-advisors for hands-off investing, while others let you pick stocks yourself.
As I have already mentioned, IG offers of 13,000 different assets as well as expertly managed portfolios which makes it suitable for various types of investing strategies.
- Fees & charges – how much will it cost?
Even small fees can add up over time, so it’s important to compare costs across different providers.
Some charge a flat monthly fee, while others take a percentage of your portfolio value.
If you plan to buy and sell frequently, look at dealing charges. IG charges £3 per trade for UK stocks and £0 for US stocks and shares.
If you’re investing small amounts, a percentage-based fee might be better. If you have a large portfolio, a flat-fee model could save you money.
It’s also important to look at withdrawal fees, particularly if you plan on dipping in and out of your ISA often.
Other types of fees that you might come across include conversion fees and custody fees. At the time of writing, IG charges a flat 0.5% conversion fee and a custody fee of £24 per quarter (unless you place 3+ during the quarter, in which case there is no fee to pay).
- Minimum investment requirements
Some platforms require a minimum deposit before you can start investing. If you want to start small, look for a provider that offers a lower minimum deposit (such as IG which does not have a minimum deposit for bank transfers).
- Withdrawal & replacement rules
Since flexibility is the whole point, it’s important to check exactly how withdrawals work.
- How quickly can you access your funds? Some providers take a few hours, others take days.
- Can you replace withdrawn investments or just cash? Some only allow cash deposits to be replaced.
- Are there restrictions on how many times you can withdraw and replace? A few platforms impose limits.
Final Thoughts
If you’re looking for a flexible stocks and shares ISA to use in 2025, the IG ISA is a great option to consider. However, it is important to shop around and compare different options before making any final decisions.
After reading this post, I recommend taking some time to review the official IG stocks and shares ISA webpage to learn more about this exciting investment account before deciding whether or not it is suitable for you.
Get started with the IG Stocks and Shares ISA here.
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Disclaimer: When investing, your capital is at risk. The value of investments can go up or down, and you could get back less than you invest. Past performance is not a reliable indicator of future results. Tax treatment depends on individual circumstances and may be subject to change.
We are compensated for referring users to IG. When you open an account with IG through our links, we receive a commission which helps us to continue providing content.
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