It seems like common sense: The 42 million Americans who will need their 401(k)s to pay the bills in retirement ought to get some sound advice.

You can imagine employees trooping into a company conference room for a couple of hours’ training on topics like asset allocation, compounding and the hazards of borrowing from your account.

But sessions like these are rare. Many employers are too cheap to hire investment advisers to run the sessions. And many are quite understandably worried that employees will sue them if the investment guidance turns out badly.

Congress has wrestled with the problem for years and now seems closer than ever to adopting a solution, as a conference committee works on alternate approaches passed last year by the House and Senate. Which is best?

The House bill would remove a longstanding law that prevents mutual fund companies from giving such advice. The measure is supported by many fund companies that administer 401(k)s, but it is opposed by the AARP and other groups worried the funds will put their own interests ahead of employees.

The Senate bill would continue to bar fund companies from this role, but would make it safer for employers to hire other investment advisers by shielding them from employee lawsuits.

Neither approach is perfect, but both are better than the status quo.

Studies by the Profit Sharing/401(k) Council of America, a nonprofit group, find only about one in five employers provide any kind of investment advice to 401(k) participants, with more than 90 percent of those that don’t citing fear of legal liability.

Yet the need for advice is clear. Surveys by consulting firm Hewitt Associates show the average employee contributes only about 8 percent of his income to his plan, while the most aggressive can put in 20 percent.

At the end of 2004, the median participant had just under $26,000 in the 401(k), which is far too little, and a quarter of participants had less than $5,000 invested.

The fact is, employees don’t need very sophisticated advice. Their investment options are limited by their companies’ plans. They need basic instruction on how to divide their contributions among various stock and bond funds based on their ages.

Beyond that, sound advice boils down to two rules: Invest every cent you can afford, and allow the money to grow for as long as possible.

Fund companies have a financial incentive to pound that message, and it’s time for Congress to remove the gag and let them do it.