The forthcoming ISA season could prove to be among the most fiercely contested on record, though market movements may result in appealing offers remaining available for longer, according to fresh analysis from Moneyfactscompare.co.uk. The research revealed that, across the previous two years, savers had secured the strongest returns on leading easy access cash ISAs between March and May compared with other periods, with numerous top rates emerging towards the end of this window.

The analysis also cautioned that savers ought to remain vigilant regarding a “loyalty penalty” as providers compete aggressively for fresh deposits. At the time of publication, the average closed easy access ISA was paying merely 2.51 per cent AER, while the leading live rate stood at 4.66 per cent AER, representing a £430 shortfall on a complete £20,000 deposit across a year.

The research further noted that the Middle Eastern conflict had “drastically changed the outlook for interest rates“. Providers may be responding to evolving expectations, potentially resulting in rates remaining elevated for an extended period.

Caitlyn Eastell, personal finance analyst at Moneyfactscompare.co.uk, said: “With the new tax year fast approaching, many savers may feel the pressure to choose an ISA before the deadline. However, while competition between providers is typically most intense in the run-up to April, the ISA season window stretches from March to May.

“Rates can continue to improve throughout this period as providers will be competing fiercely for savers’ allowances. On average over the past two years, savers have been able to maximise their deposits during the ISA rush compared to the rest of the year.

“While rates have dropped significantly since the previous tax year, the early stage of ISA season is already pushing rates up, with the top easy access cash ISA rate now sitting at 4.62 per cent gross compared to 4.31 per cent at the start of the year.

“Savers who have been waiting on the sidelines may decide to act now, especially those who still have some remaining cash ISA allowance from the 2025/26 tax year.

“However, some of the strongest deals have emerged during the latter end of this period. This means that savers who remain flexible and continue to monitor the market beyond the April deadline may be rewarded with higher returns.

“It’s crucial to find a balance, leaving money in a low-paying account for too long could mean missing out in real terms.

“Savers who have left their money in the same account are being hit with a serious loyalty penalty; the average closed easy access ISA rate pays just 2.51 per cent AER, whereas the highest rate pays over 4.60 per cent, this equates to around a £430 loss on a full £20,000 deposit over a year.

“The ongoing conflict in the Middle East has drastically changed the outlook for interest rates.

“Originally, providers were primed for a base rate cut, but now they are having to react quickly to shifting expectations. But these shifts could be positive news for savers as providers may keep rates higher for longer, allowing them to maximise their returns.”