Santander is offering cashback to customers who take out investments with the bank, up to a maximum of £100.
The offer is available to 123 World, Select or Private banking customers, who can get cashback of 0.5 per cent if they invest between now and June 15.
Customers can use the Santander Investment Hub, which includes 1,300 funds, and which the bank described as "secure, efficient and straightforward".
Alexia Kilby, head of investments at Santander UK, said: "In this low interest rate environment, we want to make investing an option for more of our customers, some of whom may not have considered investments previously.
"Our education site is dedicated to demystifying investments making them more accessible for customers who, alongside other savings options, can benefit from our new competitive cashback aimed at contributing towards their long-term investment goals."
Customers can invest from just £20 a month or a £100 lump sum. As well as its DIY hub, Santander offers a financial planning service, with face-to-face advice from financial planning managers or private bankers.
Adam Rutter, at Findlay & Company in Dundee said the offered was aimed at getting current customers to use their Isa allowances.
"If you were going to do this anyway then it is a reasonable offer. However if you were thinking of opening an account with Santander then putting £20,000 into an Isa you would get the cash back but long term you would be in a restricted offering with limited and expensive funds," he added