Martin Lewis outlines the 'top deals' for savings accounts British savers are being urged not to waste their annual £20,000 Isa allowance as experts warn major rule changes are looming for millions. Consumer group Which? says many households are overlooking a string of hidden tax perks attached to Individual Savings Accounts - at a time when frozen tax thresholds are dragging more workers into higher tax bands. The warning comes as competition among banks and building societies intensifies, with the number of cash Isa deals hitting a record high this spring. According to Moneyfacts data, there were 712 cash Isa accounts available on April 1, 2026 - the highest number ever recorded. Average instant-access cash Isa rates also rose from 2.61% to 2.73% AER. But experts say the real attraction is not just tax-free interest - it is the growing importance of shielding savings from the taxman as fiscal drag tightens its grip. Office for Budget Responsibility estimates that by 2030-31 another 4.8 million people will be dragged into the higher-rate tax bracket because income tax thresholds have been frozen while wages continue to rise. That means savers who once paid 20% tax on savings interest could eventually face a 40% hit instead. Matthew Jenkin, senior writer at Which? Money, said savers should not underestimate the long-term value of protecting money inside an Isa wrapper. He highlighted lesser-known Isa advantages that many households fail to use. READ MORE: NatWest '£150,000' update in big change for some UK households READ MORE: Update as NS&I Premium Bonds 'could cost savers thousands' Protection from Capital Gains Tax Profits made inside a stocks and shares Isa are entirely free from CGT, unlike investments held outside the tax-free wrapper where gains above £3,000 are taxable in the 2026-27 tax year. Experts say investors can also use a “Bed and Isa” strategy - selling investments held outside an Isa before repurchasing them within the tax-free account. Cash Isas outperform many standard easy-access savings accounts Moneyfacts figures show the average instant-access cash Isa paid 2.73% on April 1 compared with 2.44% for non-Isa accounts. On a £10,000 balance, that could leave savers roughly £29 better off over a year. However, experts warned fixed-rate savings accounts can still offer better deals than fixed cash Isas. The research found one-year and multi-year fixed savings accounts have generally beaten equivalent Isa products in recent years. Among the recent market-leading deals highlighted were a 5% easy-access saver from Cahoot and a 4.52% one-year fixed cash Isa from Investec. Looming restriction planned for April 2027 Under proposals announced by the Government, under-65s will only be able to hold £12,000 in cash within an Isa. Anyone wanting to use the full £20,000 allowance would need to place the remaining £8,000 into investments through a stocks and shares Isa. Inheritance advantages attached to Isas Bereaved spouses and civil partners can inherit both the savings and the tax-free status through an Additional Permitted Subscription allowance, introduced in December 2014. Flexible Isas These savings accounts can prove useful for emergency savings because withdrawals can be replaced within the same tax year without affecting the annual allowance. Younger savers with student loans could benefit Because Isa interest is tax-free, it does not count as taxable savings income in self-assessment calculations — potentially helping borrowers avoid higher student loan repayments.