Financial advisors can solidify their relationship with more of their millionaire clients by helping them write complete financial plans, says a recent study by the Spectrem Group, which revealed that only slightly more than half have a written plan.

The survey also shows millionaires need to talk with advisors about tax issues and strategies, says the Spectrem Group Millionaire Investors study, Relationships with Advisors. The study included 1,492 people with between $1 million and $5 million in investable assets.

About half of those surveyed have established their cash flow needs for retirement, although nearly 60% of those surveyed are already retired. And only half have considered implementing tax advantaged strategies.

"While it is unclear what may happen with taxes in the near future, millionaires need to be educated regarding potential tax strategies that may be beneficial in the future," Spectrem says.

Most also have not talked with their advisors about long-term health care needs.

Despite these shortcomings, the majority of those surveyed, 70%, are satisfied with their advisor, and even more, 77%, are satisfied with their advisors' knowledge and expertise of financial matters. However the overall satisfaction level goes down for those under 54 years of age (60%) compared to those over 65 (73%).

"Younger millionaires have higher expectations of their advisors and will require advisors to continue to expand their expertise, as well as their communication methodologies," the survey says.

The overwhelming choice for a primary advisor, at 37%, is a full-service broker followed by an independent financial planner or independent investment advisor (RIA), at a total of 26% for the two.

One of the worst things an advisor can do is not return phone calls or emails, and the largest group of millionaires (41%) would like to be contacted every month.