The minimum balance for the Isa is £1,000, while the maximum balance in the current year is £20,000 in accordance with the HMRC's 2017/18 tax year Isa allowance, however, previous years' Isas can be transferred in with no upper limit.

The specialist bank is offering these as portfolio Isas, which means that customers can open one of each Isa and split this year's allowance between the two.

The bank – which has built a loan book of over £900m –  is hoping to lend a further £1.5bn to SMEs in 2018.

“Since our launch [in September 2015], we have attracted over 15,000 deposit customers whose savings have helped fund our lending and enabled us to support numerous UK businesses in achieving their growth ambitions,” said Joel Perlman, co-founder of OakNorth (pictured above).

“As we look ahead to 2018, we are keen to continue building our high-quality loan book, lending a further £1.5bn to SMEs, so we felt now was the right time to expand our product range and hopefully attract even more customers.”

OakNorth offers a range of savings products to both individuals and businesses.

“The UK's largest banks continue to offer pitiful returns – 0.51% on average for 12- and 24-month fixed rate cash Isas – and many savers have been disillusioned by the fact that these banks have not passed on the recent interest rate rise to them,” added Joel.

“The launch of our new competitive fixed rate and easy access cash Isas will hopefully be a step in the right direction towards rectifying this, giving both our existing and prospective customers the opportunity to make their savings go further.”