The Financial Services Authority (FSA) has voiced concerns about advisers' gap-fill progress ahead of RDR implementation at the end of the year.
Research conducted by the regulator suggests that less than 40% of those identified as needing to complete gap-fill activity have done so.
With fewer than nine months to go until RDR rules are rolled out, the FSA's figures suggest 39% of the 67% who require gap-fill have completed it, while 19% have yet to start.
More than four-in-ten (42%) have begun the process but still have more to do, according to the data.
One of the RDR's requirements is for every retail investment adviser to have a miniumum qualification level measured at QCF Level 4.
Advisers who already had a Level 4 qualification must complete gap-fill activity - or take another exam - to bridge any knowledge gaps between what was tested in their original exam and what an adviser would be expected to know today.
Meanwhile, FSA research also suggests many more advisers have now reached QCF Level 4 standard.
The proportion of advisers with an appropriate qualification has increased from 50% to 71%, it said, while 93% of advisers are still on track with their prediction to complete the appropriate qualification in time.
Linda Woodall, head of investments department at the FSA, described gap-fill as "one of the weaker" areas in terms of adviser preparedness for RDR during a speech at the Financial Times Intermediary Forum in London yesterday.
"It is clear that firms have made good progress, but we want to see more of you getting the appropriate qualification and identifying where you need to do gap-fill - remember the accredited bodies can help you with this," she said.
In other statistics presented during the speech, Woodhall said that 69% of advisers have developed and begun to implement a plan to be completely RDR compliant by 2013.
However larger firms were some way behind smaller firms with just 36% having done so.
The figures come from a number of surveys conduced by the FSA over the last few months.
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