Aegon is to pay out €40m (£34m) in compensation to 30,000 customers who were overcharged for unit-linked products sold over a nine-year period.
Business Week reports the Dutch supreme ruled on Friday that between 1989 and 1998, the holders of Koersplan paid excessive premiums and were not aware how much Aegon charged for term life insurance.
Aegon says it will now consider if any further compensation is needed for clients not represented in the court. As many as 700,000 Koersplan policies were sold.
Last year, Aegon made a redress provision of €265m and said it would reduce future costs for customers with certain unit-linked policies.
In 2009, the insurer said it would set aside as much as €250m to settle allegations that it overcharged some customers of unit-linked policies sold before 2008.