The rates of the top-paying, variable-rate cash Isas have fallen by almost 30pc since September, analysis by Telegraph Money has revealed.

At the start of last September, Al Rayan offered the top variable rate of 1.55pc. Today, Hinckley and Rugby Building Society and The Family Building Society up to 1.2pc.

Al Rayan’s easy access Isa currently pays just 0.5pc.

While some providers began quietly reducing rates in anticipation of a cut to Bank Rate last summer, many held fire until after the announcement.

Today’s best variable deals

Savers can put up to £20,000 in a cash Isa for the 2017-18 tax year.

Here, we name the best paying variable cash Isas available right now. These accounts allow varying degrees of access and the rates can go up and down. Some of the higher paying accounts come with catches such as notice periods and limited withdrawals.

Don’t forget that there are alternative accounts that could pay more on your savings pot, such as high-paying current accounts.

Hinckley and Rugby Building Society offers a variable Isa that pays1.2pc. Savers must have at least £500 to open the account by post or in branch. Old Isa transfers are not allowed from other providers. However they are permitted from other Hinckley Isas.

Hinckley charges customers a £25 fee to transfer all or part of their Isa balance to another approved provider. This Isa is also a notice account. Customers must tell Hinckley they wish to make withdrawals 120 days in advance or face loss of interest.

The Family Building Society also pays up to 1.2pc but this depends on your balance.

Those with savings of £3,000 to £14,999 will earn 1pc, customers with balanes of £15,000 to £29,999 will get 1.1pc and those with more than £30,000 will earn 1.2pc.

The Isa is flexible, which means money can be drawn out and replaced in the same tax year without it affecting the subscription. Withdrawals are subject to 35 days notice.

Transfers of old Isas are allowed.

Paragon Bank, Leeds Building Society and the AA all offer easy-access Isas that pays 1.16pc. Paragon’s account can be opened online with £1. Leeds BS customers must have at least £1,000 to save.

The AA account can be opened online with £100. It only pays 1.16pc for the first 12 months which includes a 0.96pc bonus.

The Post Office offers 1.15pc. The Isa is easy access, online-only and can be opened with £100. The rate includes a 0.9pc bonus which is only paid for the first 12 months.