Aegon has cited the implementation of the RDR as the reason for a £4m 'negative effect' today.
In its third quarter results to 30 September 2012, the firm reported pre-tax earnings of £20m, up from £8m in the same period a year ago.
This was due to the implementation of a cost reduction programme which was launched in June 2010 but problems were caused by RDR.
The report read: "These positive impacts were partly offset by a £4m negative effect from adverse persistency, which the UK insurance industry is experiencing in anticipation of the Retail Distribution Review."
The firm's cost reduction programme also saw operating expenses fall by 30 per cent to £73m.

Net income increased to £30m due to higher underlying earnings and gains on investments but new life sales declined by seven per cent to £163m, down from £175m in the same period a year ago. However, the firm said this "reflected an expected reduction in pension sales" and was partly offset by sales on the Retirement Choices platform.
Platform sales increased as new advisers joined the Aegon Retirement Choices platform which recently had a workplace solution added.
Aegon UK chief executive Adrian Grace said the firm had spent time changing its product set and services ahead of RDR.
He said: "Over the past couple of years, life and pension providers have essentially been faced with two choices. They could either tinker with their product set and drive new business to an outdated model up to the end of this year, after which they will have to radically overhaul their proposition, or they could transform their product set and services ahead of the RDR.
"We have chosen the transformation path. What we've done is streamline our business to be more focused and profitable and have built strong foundations with innovative new propositions.
"We are confident our actions put us at a competitive advantage to grow new business that is aligned to the new legislation and meet the ever-evolving needs of our customers."