Most investors likely assume their advisors consider their clients’ best interests to guide their investments, but that hasn’t been required under federal rules for financial professionals.

That’s about to change.

A new rule, unveiled last week by the U.S. Department of Labor, will hold advisors to a stricter standard for retirement advice, minimizing potential conflicts of interests that have led savers into sometimes expensive or complicated investments.

The rule requires advisers to abide by a “fiduciary” standard that puts clients’ interests before their own profits. Currently, stockbrokers who work on commission selling investment products are required to meet a lower standard, making recommendations that are “suitable.”

As the rule was being formulated, members of the financial planning industry complained the overhaul would hurt the middle-class investors it’s meant to help, burdening clients with higher costs, fewer investment choices and less access to advice. It’s still expected to boost costs, which likely will be passed to consumers, and possibly force advisors out of some business segments, industry experts say. But the final rule has been met with less alarm than previous versions.

Most agree the rule will usher in a shift in the way people save for retirement.

“I think people are underestimating how historic this is,” said Scott Puritz, Managing Director of investment management firm Rebalance. “We believe that 20 years from now, this will be looked back on as a turning point in managing retirement savings and making investing safer for all Americans. At its core, what the rule will do is shine a big spotlight on all of these hidden fees and conflicts of interest.”

The Labor Department, which has overseen retirement savings since the 1974 enactment of the Employee Retirement Income Security Act, or ERISA, estimates that conflicts of interest have meant retirement savers earn annual returns about a percentage point lower than they would have, a gap amounting to $17 billion in losses a year.

Besides making changes in the way they offer advice, advisory firms will need to make changes in the way they distribute and price products.

Paul Dougherty, national president-elect for the National Association of Insurance and Financial Advisers and an agent in Hyattsville, said he was encouraged by revisions to the rule, first proposed last year, that take into account some of the industry’s concerns. But the rule still has its drawbacks, he said, citing questions about liability for advisors and their firms and how some products will be restricted.

“It’s still going to be very costly to implement and to ensure you’re in compliance with all the aspects of the rule,” Dougherty said.

“We felt comfortable with the suitability standard because clients were telling us what’s appropriate for them, and sometimes that evolves,” he said. “Those of us that meet with clients every day and try and educate them and help usher them through the planning for retirement would tell you we’re always considering the best interest of the client — otherwise we’d be out of business.”

At least one Republican member of Congress blasted the Obama administration for what he said amounted to bypassing the Securities and Exchange Commission to defer to an agency without capital markets expertise.

“This is Obamacare for your IRA and 401(k), and just like Obamacare, this complex rule will likely raise your costs and potentially limit your choices,” said Rep. Jeb Hensarling of Texas.

But consumer advocates cheered the Labor Department’s announcement.

Firms that handle 401(k) account rollovers when employees leave a job have long used loopholes “to avoid their obligation to act in the best interest of the customer, and this rule changes that,” said Barbara Roper, director of investor protections for the Consumer Federation of America. “People have no idea when they go to see an advisor, that that advisor may be paid two times or 10 times as much more to sell one product over another. … As long as it’s suitable, that’s perfectly legal.”

The rule should protect the many federal workers and employees who withdraw their investments from thrift saving plans — the federal version of a 401(k) known for low administrative fees — within a year of retiring or getting new jobs, said Jessica Klement, legislative director for the National Active and Retired Federal Employees Association. Often those workers or retirees were contacted by firms promising a similar rate of return on similar types of funds but with much higher fees that are not always disclosed, she said.

“The law would prevent advisors from acting in their own interest instead of in clients’,” Klement said.

Some analysts said it’s difficult to predict the rule’s long-term impact, especially on publicly traded traditional asset managers that service IRA accounts.

“With almost all of the asset managers we cover being primarily fund manufacturers, providing the investment products that that advisors and broker/dealers use to populate IRAs and other type of accounts, the long-term impact on their businesses depends on the product selection changes that take place within these channels,” wrote Greggory Warren, a Morningstar equity analyst, in a report last week.

The rule likely will push more IRA accounts into fee-based structures, “a boon for low-cost exchange-traded fund providers like BlackRock and Vanguard,” Warren said.

And he envisions a spike in growth of asset management by robo-advisors, or online wealth management services, which tend to use low-cost offerings such as Exchange Traded Funds, as full-service advisors become less willing to take on clients that will increase compliance costs.

Despite some changes in the final rule, “the intent of the regulation — aimed at making it harder for advisory and broker-dealer firms to encourage advisors to steer clients into products with higher fees at the expense of long-term returns — still stands,” Warren said.