If you’re looking for the best place to grow your savings tax-free, here’s a clear comparison based on the latest offers. We’ve ranked them by overall value, flexibility, and real-world earning potential - with XTB taking the top spot.
If you’re looking for the best place to grow your savings tax-free, here’s a clear comparison based on the latest offers. We’ve ranked them by overall value, flexibility, and real-world earning potential - with XTB taking the top spot.
1.XTB: Best Overall
Why it’s 1:
XTB stands out with the highest headline rate, no fees, and full flexibility - making it ideal for both new savers and those who want easy access.
Key features:
- Type: Flexible
- Interest rate: 6% AER (variable, promotional)
- Withdrawals: Unlimited
- Minimum deposit: £0
- Fees: £0
Important details:
- XTB offers 6% AER to new clients that open an account between 1 March and 30 April 2026 for 90 days from ISA open date.
- This is made up of a 4% variable rate + 2% boosted AER for new clients. T&Cs apply.
Verdict: Best short-term return and most accessible option overall.
2.Trading 212
A strong flexible option with a competitive boosted rate for new users.
Key features:
- Type: Flexible
- Interest rate: 4.4% AER (variable)
- Withdrawals: Unlimited
- Minimum deposit: £1
- Fees: £0
Important details:
- For new customers only: 4.4% = 3.6% variable + 1-year 0.8% bonus.
- Lower 3.6% rate applies to transfers of previous years’ deposits.
Verdict: Great balance of flexibility and decent returns, but lower than XTB.
3.Plum
A fixed-rate style offer with a longer promotional period.
Key features:
- Type: Fixed-style (promo-based)
- Interest rate: 4.32% AER
- Withdrawals: Unlimited
- Minimum deposit: £1
- Fees: £0
Important details:
- Promotional rate for new clients for the first 12 months.
- Made up of 2.54% variable + 1-year 1.76% bonus.
- No bonus on transfers in.
Verdict: Solid 12-month option, but less flexible in how the bonus applies.
4.eToro (with Moneyfarm)
A more structured offer with conditions attached to maintain the bonus.
Key features:
- Type: Flexible
- Interest rate: 4.47% AER (variable with bonus)
- Withdrawals: Unlimited (with limits for bonus)
- Minimum deposit: £500
- Fees: £0
Important details:
- eToro has partnered with Moneyfarm.
- Boosted rate is calculated daily and paid after 12 months.
To maintain the bonus:
- Keep at least £500 balance
- Limit withdrawals to three per year
Standard introductory rate (first 12 months): 3.67% AER variable.
Verdict: Competitive, but conditions make it less flexible than it appears.
5.Moneybox
A decent rate, but restrictive withdrawal rules hurt its ranking.
Key features:
- Type: Fixed-style (bonus-dependent)
- Interest rate: 4.47% AER advertised
- Withdrawals: Limited for full rate
- Minimum deposit: £500
- Fees: £0
Important details:
- Pays 4.32% including a 0.87% variable 12-month bonus.
- Rate drops sharply to 0.75% if you make more than three withdrawals a year.
Verdict: Good if you won’t touch your money - otherwise not ideal.
Frequently Asked Questions (FAQs) - Flexible Cash ISA
Best ISA Interest Rates in the UK: How XTB Compares
Why XTB Offers One of the Best Low-Cost ISAs in the UK
This content has been created by XTB S.A. This service is provided by XTB S.A., with its registered office in Warsaw, at Prosta 67, 00-838 Warsaw, Poland, entered in the register of entrepreneurs of the National Court Register (Krajowy Rejestr Sądowy) conducted by District Court for the Capital City of Warsaw, XII Commercial Division of the National Court Register under KRS number 0000217580, REGON number 015803782 and Tax Identification Number (NIP) 527-24-43-955, with the fully paid up share capital in the amount of PLN 5.869.181,75. XTB S.A. conducts brokerage activities on the basis of the license granted by Polish Securities and Exchange Commission on 8th November 2005 No. DDM-M-4021-57-1/2005 and is supervised by Polish Supervision Authority.
