The offer is available until 25 April and is limited to certain clients.

The offer is only available to new clients to HL or existing clients who do not have a cash ISA who deposit £10,000 or more into the savings products within the cash ISA platform.

Savers can earn up to 5.28% AER if they deposit £10,000 or more into the highest paying cash ISA product on offer on the platform taking into account the £25 cashback, HL said.

According to analysts MoneyfactsCompare.co.uk the market-leading cash ISA rate is currently offered by Plum, which pays 5.06% gross/5.17% AER on £100. However the rate includes a 0.86% bonus for 12 months, and savers may face a reduction in the interest rate paid if they make four or more withdrawals per year.

Mark Hicks, head of active savings at Hargreaves Lansdown, said: “The offer is ideal for those rushing at the last minute to make the most of their ISA allowance this year and for those early birds in the next tax year that have already filled their allowance.”

HL’s cash ISA platform allows clients to manage their cash ISA portfolio across multiple banks, in one account. However the total number of banks on the platform is just six.

Since launching the platform in early February, HL has added Charter Savings Bank and LHV to its bank panel.

The cashback offer is only payable to:

• Existing HL clients that don’t currently have a cash ISA open.
• Any new clients to HL that open a cash ISA before 25 April.
• Clients only qualify for the bonus once.