The best ISA (Individual Savings Account) rates as recommended by Martin Lewis in 2025 for cash ISAs include:

• Trading 212 Cash ISA offering 4.82% for 12 months (4.1% variable plus a 0.72% newbie bonus). This account allows easy access with unlimited withdrawals.
• Skipton Building Society Cash ISA offering 4.12%, a top "big name" with unlimited withdrawals but no transfers in except current tax year deposits.
• Cynergy Bank Fixed-rate ISAs with 4.3% for one year and 4.2% for two years.
• Other notable fixed-rate ISAs include Paragon Bank at 4.28% (15 months) and Vida Savings at 4.25% (one year).
• For Lifetime ISAs, Moneybox offers 4.94%, Plum 4.6%, and Tembo 4.33%, all with state bonuses up to £4,000 per year.
• Martin Lewis highlights accounts like Chip and Trading212 offering nearly 5% easy access rates.

Cash ISAs let you save up to £20,000 tax-free for the 2025/26 tax year. Easy access ISAs allow withdrawals anytime, while fixed ISAs typically require locking money in for a set period at a guaranteed rate. The current market top rates reflect a mix of well-known providers and newer platforms with competitive bonus rates for new customers. The top easy access rates are around 4.8-4.9%, while fixed rates can reach just above 4.3%. ISA limits and rules could be subject to change soon, possibly lowering the max deposit from £20,000 to £4,000 according to government rumors, so maximizing current ISA allowances is timely. These highlighted ISAs represent some of the best interest rates available in September 2025 according to Martin Lewis and MoneySavingExpert updates.