Skipton Building Society has boosted the rate on its 18-month cash Isa to 4.55 per cent, making it the best overall tax-free rate available to savers.

The account can be opened online, on app, in branch or by phone and is available to new and existing customers.

It accepts transfers in with savers needing to deposit £500 to open. The next best rate offers 4.53 per cent but requires fixing for either three or five years.

Meanwhile, Investec offers 4.52 per cent on a one-year fix and Santander 4.5 per cent on a 12-month bond.

For the current financial year, all savers have a tax-free allowance of £20,000. From April 2027, the cash limit for under 65s drops to £12,000 a year.

Money cannot be withdrawn from the Skipton account and early closure is subject to a 90 days' interest penalty.

Up to £1million can go into the account, but cash at Skipton – like all providers covered under the Financial Services Compensation Scheme protection – is only protected up to £120,000.

Skipton also boosted the rate on its 'easy' access offering last week to 4.07 per cent – savers can only make penalty-free withdrawals twice from it.

There are far better rates available in the independent This is Money savings tables, including 4.51 per cent from Trading212* and 4.31 per cent from Plum*.

Skipton is Britain's fourth biggest building society behind Nationwide, Yorkshire and Coventry and has 82 branches.