Best Fixed Rate Cash ISAs in October 2026

Shawbrook's 5 Year Fixed Rate Cash ISA is currently the market-leading Cash ISA at 5.25%, sitting 2.15% above CPI inflation of 3.1% (Aug 2026), which makes it a genuinely useful real-terms return for anyone comfortable locking money away for five years. It accepts transfers in and works from a £1,000 minimum, so it suits savers consolidating existing ISA pots as well as new money.

The main catch is straightforward: your money is tied up for the full five years, so this is only right for funds you are certain you will not need.

Tandem Bank's 3 Year Fixed Rate Cash ISA pays 5.13%, which sits above the cash ISA market average though 0.12% behind the category leader at 5.25%. At 2.03% above August 2026 CPI of 3.1%, it does at least offer a meaningful real return, which makes it worth considering for savers who want to lock in a tax-free rate for three years.

The catch is the early withdrawal penalty of 270 days' interest, so this suits someone confident they will not need the money, up to the £20,000 maximum, before the term ends.

Castle Trust Bank's 5 Year Fixed Rate e-Cash ISA pays 5.12%, which sits above the cash ISA market average but 0.13% behind the category leader at 5.25%. At 2.02% above CPI inflation of 3.1% (Aug 2026), the real return is decent for anyone willing to commit for the full five years.

The hard catch is that there is no access until maturity, so this suits savers who are confident they will not need the money for the entire term. If you want a near-identical rate with the same term, Tandem Bank's 5 Year Fixed Rate Cash ISA offers 5.13%.