Savers earning low returns on individual savings accounts (Isas) should consider transferring to fixed-rate deals - or look to switch when Isa competition picks up towards the end of the tax year, experts said.

The average variable-rate Isa now pays less than 2.5 per cent, according to Defaqto, a market analyst, but some rates are as low as 0.1 per cent. Halifax’s Isa Saver account pays this return on balances under £3,000, and only 0.15 per cent up to £12,000. Isas accepting transfers from other providers offer up to 4 per cent, with both fixed and variable- rate deals available (see table below).

Returns are expected to fall further following this month’s 0.5 percentage point base rate cut, with more Bank of England reductions possible in the spring. Transferring to a fixed deal protects savers from rate cuts.

However, providers also tend to launch higher-paying Isas near the end of the tax year, aimed at savers seeking to use up their £3,600 annual allowances and at those taking out new Isas from April 6.

Kevin Mountford, head of savings of Moneysupermarket.com, a comparison service, said that there was generally a “spike” in Isa rates in March. Moneyfacts, the rate service, said competition for savers could result in Isa offers about 0.5 percentage points above the normal market level, with fixed rates often particularly competitive. “Many savers are organised to invest on the first day of the new tax year, so providers bring out their deals a few weeks before,” said Rachel Thrussell, Moneyfacts’ head of savings.

However, savers who transfer to current variable-rate deals could lose out. After the series of base rate reductions since October, many providers are not up to date with their cuts. “You could find you move Isas and then the new account falls lower than your previous deal,” warned Thrussell.

For some savers with bigger Isa balances, it could still be worth transferring now to pick up extra interest, even if this meant switching again later on, she suggested. But the length of time some banks and societies take to transfer Isas could also negate any short-term benefit. Transfers should go through within a month but, in practice, can take longer.

Mountford said that in spite of rate reductions, cash Isas were still attractive as returns are tax-free. For a higher rate taxpayer, a 3.6 per cent Isa rate is worth 6 per cent gross on a normal savings account.