However, the maximum contribution is established by using a formula tied to the third quarter Consumer Price Index for all urban consumers. That's normally not a concern for investors because inflation has steadily increased. What's potentially troubling is that the CPI-U figure for this year, to be released on Oct. 15, is expected to be lower than a year earlier.

The CPI-U measures the average change in the prices of goods and services including food, clothing, shelter, fuel, drugs and other day-to-day items bought by U.S. urban consumers. It is released by the U.S. Department of Labor.

The CPI-U jumped more than 5% in the third quarter of 2008 compared with the same period a year earlier, which bumped up the contribution limit for this year. But, since March 2009 the index has come in below the corresponding 2008 value. It's anticipated that this year's third quarter will be lower than the 2008 figure. That means for the first time ever, the Internal Revenue Service is faced with the likelihood that the maximum contribution level now at $16,500 will be lower than the year before. If current assumptions are correct, the CPI-U number will lower the amount you can contribute to your 401(k) in 2010 to $16,000.

That's not a huge problem, really, because only about 10% of workers contributing to a 401(k) pay in the maximum allowed. The issue is that a lower contribution level is contradictory to the "save more, not less" message the industry has been telling people since last year's economic collapse.

About $2.7 trillion was lost in 401(k) and individual retirement accounts between September 2007 and May2009, says the Urban Institute, a Washington-based independent research group.

Investment advisers say the best way to regain some of that lost value is to continue to contribute and keep money in the stock market to take advantage of gains that are bound to come with economic recovery. Historically, the S&P 500 returns about 9.7 percent annually.

It's critical that they're saving for retirement, and it's critical over the course of their careers that they incrementally increase their savings, if that limit goes down, it's somehow sending a message that it's OK to cut back.

A spokesman for the House Committee on Education and Labor, which oversees legislation regarding retirement issues, declined to comment and a spokeswoman for the Ways and Means Committee, which handles revenue issues, did not immediately return calls seeking comment.