Cash ISA Guide: Best Cash ISA Rates UK 2026/27 — Easy Access, Fixed and How to Choose the Right Account
The Bank of England has now held the base rate at 3.75% for seven consecutive months — the longest pause since the cutting cycle began in August 2024. Yet the best easy-access cash ISAs still pay 4.51% AER, a full 1.71 percentage points above May 2026's CPI inflation of 2.8%. That is a 1.71% real return, tax-free, on cash you can withdraw tomorrow. HMRC dropped a fresh variable into the ISA calculus on 23 June 2026: cash interest held inside stocks and shares ISAs will now be taxed at 22%, removing a loophole that previously let investors shelter cash inside an equity wrapper. The move sharpens the line between cash ISAs and S&S ISAs — and makes the choice of wrapper more consequential than it has been in years. For the 2026/27 tax year, every UK adult has a £20,000 ISA allowance. Use it. From April 2027, the allowance for under-65s drops to £12,000. Money you shelter this year stays tax-free permanently. Here is exactly where to put it, how to choose between easy access and fixed, and why — for higher-rate taxpayers especially — leaving ISA allowance on the table is the most expensive mistake you can make in 2026.