The partnership approach has worked, it says, because many advisors have in their careers worked with only three or four plans and, as a result, don't view themselves as retirement plan experts. Tying in with Paychex helps them become more adept at chasing group retirement plan business.

Paychex has been a payroll and human resources company since it was founded in 1971. It entered the 401(k) record-keeping business in the mid-1990s, targeting firms with fewer than 50 employees, in part because they represented an often-ignored corner of the market, said Ken Burtnick, senior product manager at Paychex.

Paychex officially announced its new initiative in the fall of 2012; it had hired Rich Brindisi as senior marketing manager in late 2011 to get things in order and head up the initiative.

It also carved out a sales force to pursue relationships with financial advisors and plan sponsors.

The company helps advisors in part by providing them with the expertise they need through articles, white papers, Web seminars and in-person seminars.

Paychex also set up dedicated account managers to support its newly integrated financial advisors and their clients.

Additionally, Paychex created a website and database that allows broker-dealers to search and cross-reference mutual funds available on the platform with funds available on their own platforms.

"Many advisors and broker-dealers are trying to promote their advisors to go out and expand into retirement plans," said Brindisi, and so partnering with Paychex allows them to do so more readily.

Experienced advisors also have partnered with Paychex.

Among them: Andrew Betts of Bickling Financial Services in Lexington, Mass.

"By partnering together we are able to provide services that would ordinarily be directed to bigger plans, but can now be offered down to (those) $1 million in size," Betts said. "We are able to deliver some of that service to smaller plans and Paychex is able to keep a good client."

"It also gives them the opportunity to step up their game and focus on the type of support the licensed representatives need to service these plans. They certainly have improved their service model over the last few years," Betts said.

Bickling is working with Paychex on eight to 10 mid-size plans, each between $1 million and $10 million in assets.

"It's a real win for the client. The client could go to another company if they wanted to. (But) they didn't want to (find a new) payroll company. Very often, at that size, payroll and the plan come hand-in-hand. The company is able to stay with the folks they like working with, rather than feeling an obligation to move both pieces of their business elsewhere," Betts said.

Paychex, not surprisingly, isn't alone. Numerous rivals are now targeting the smaller plan market because of the growth potential.

"There is a realization in the marketplace that people are not ready for retirement," which has spurred interest in 401(k) plans across the board, said Ary Rosenbaum, a New York-based ERISA and retirement plan attorney.

Paychex and others also were spurred into action by a 2011 Department of Labor rule allowing financial advisors to work more closely with plan sponsors on their retirement plans. The change opened up opportunities for smaller companies to bundle investment advice as part of their 401(k) and IRA plans.

The rule allows fiduciary investment advisors to receive compensation from investment vehicles they recommend if the investment they provide is based on a computer model that is certified as unbiased, or the advisor is compensated on a level-fee basis, meaning the fee doesn't vary based on the investments a participant selects.

"That was a unique and very important change," Rosenbaum said.

He added that new fiduciary rules now being developed by the SEC and Department of Labor also will soon mean big changes for financial advisors, particularly broker-dealers. Many will have to decide whether they want to change their status or commit to higher standards than they have had to meet in the past.

"It is not surprising that Paychex would want to get in there somehow," Rosenbaum said.

"The financial advisory community may have been skeptical to move from the model we were in to the new model, but the responses we are hearing – as evidenced by staff and feedback from broker-dealers, advisors and Defined Contribution Investment Only firms – is that they are pretty excited about what we've got going on here at Paychex," said Burtnick.

Frank Nargentino, a certified financial planner and senior vice president of investments for JHS Capital Advisors in Plainview, N.Y., is certainly enthusiastic about it all.

"Whether it is issues on swapping out different funds on the platform or reporting on plans … the service is fantastic," he said.