Both help you save, but they're taxed differently. Here's a clear UK comparison to help you decide where to put your money in 2026.
The biggest difference is how interest is taxed. Interest earned inside a Cash ISA is completely tax-free. Interest from a regular savings account is potentially taxable, although the Personal Savings Allowance means many people pay no tax on modest amounts of savings interest.
Each tax year you can pay in up to a set ISA allowance (£20,000 across your ISAs for 2026/27). Anything you save within that limit grows free of UK tax on interest, dividends or gains, depending on the ISA type.
| Feature | Cash ISA | Savings Account |
|---|---|---|
| Interest tax | Always tax-free | Taxable above allowance |
| Annual limit | £20,000 (ISA allowance) | No limit |
| Access | Varies (easy or fixed) | Varies (easy or fixed) |
| Best for | Larger / long-term savings | Smaller / flexible savings |
Basic-rate taxpayers can usually earn a chunk of savings interest tax-free each year through the Personal Savings Allowance; higher-rate taxpayers get a smaller allowance. If your savings interest stays under your allowance, a regular account may be just as tax-efficient as an ISA — but once you exceed it, the ISA's tax-free status becomes valuable.
If you have a large amount saved, expect to earn significant interest, or want certainty that your interest stays tax-free, a Cash ISA is often the safer choice. For smaller, flexible savings where interest stays below your allowance, a regular account with a strong rate can work just as well.
▶ Use the free UK Savings & ISA Calculator