LloydsTSB has launched a fixed rate Isa offering 3.20% for savers with £30,000 to deposit.
But for those who have less than £30,000 to invest, the rates are less good.
People with deposits of between £3,000 and £8,999 only get 1.5% for their cash, with the next level of interest not kicking in until £15,000.
This compares with the Which? current cash Isa Best Buy, the E-cash Isa from Scottish Widows Bank (which is part of the Lloyds group) that offers 3.1% AER for deposits of £10 and over with instant access.
Single deposit only
Other conditions on Lloyds’ fixed rate Isa mean customers can only make a single deposit for the 2009/2010 tax year, however they can put in savings from previous years.
Janet Pope, LloydsTSB spokesperson, said: ‘Now is not the easiest time to be a saver with interest rates at an historic low.
‘This makes it more important than ever to utilise the tax free allowance available, but with the 2008/2009 tax year end looming on April 5th, six out of ten Isa holders have not yet taken full advantage.’
A Lloyds survey found nearly half of Isa savers will choose fixed savings rates, something the bank attributes to uncertainty over interest rates.
The current climate means that just 11% of savers feel comfortable with a rate that could change.
Just 63% of Isa holders have deposited the full £3,600 allowance this tax year and 40% say they hold savings in a non-Isa account.