Some 50,000 Aviva life insurance customers are due for a refund after the insurer spotted payment irregularities.
Aviva believes that around 50,000 customers have been affected by the overcharging, the vast majority of whom have been overcharged by £100 or less.
The error relates to former Friends Life customers, a company acquired by Aviva in 2015.
Customers with index-linked life insurance policies have been paying higher premiums than they should have and will now be refunded.
This could potentially cost the provider millions of pounds to correct.
A spokesperson for Aviva told Moneywise: “We’re contacting all affected customers to apologise and are committed to ensuring they are not financially disadvantaged as a result.
“This was caused by an IT system error, which did not accurately reflect all the terms and conditions relating to premiums. Following a meticulous investigation, this has now been fixed.
“The affected policies are Friends Life – now Aviva – index-linked protection policies, which relate to life insurance, critical illness and income protection.”
The company has confirmed that there is nothing customers affected need to do as it will be in touch to arrange refunds.