⏳ Reading Time: 7 minutesISAs (Individual Savings Accounts) are one of the UK’s most powerful vehicles for tax-efficient saving and investing. With generous tax advantages and a wide range of account types, they can help you build wealth over time, provided they are used wisely.
However, many savers and investors make costly ISA mistakes that can reduce returns, trigger avoidable tax, or even lose the benefit of an annual allowance.
In this Moneyfarm blog we will take a closer look at the most common ISA investing mistakes and how you can avoid them.
1. Failing to Use Your ISA Allowance Before the Deadline
Every UK resident over 18 is entitled to an annual ISA allowance of £20,000 for the 2026/27 tax year — the same amount that has applied since 2017/18.
