(Bloomberg) -- Americans aren’t saving enough forretirement.

True, this has been a refrain for longer than many canremember.

But now some disturbing numbers show exactly how bad it’sgotten. Two-thirds of all Americans don’t contribute anything to a401(k) or other retirement account availablethrough their employer.

Millions aren’t saving on the job because they either don’t haveaccess to a workplace retirement plan or they do but aren’t puttingmoney in it. Many just can’t spare the cash, but a new analysisshows there are other reasons, too.

Related: Support for state-run retirement plans isstrong

Until now, the exact size of the problem has been unclear.Surveys can be unreliable: Small businesses are difficult toassess, and many workers just don’t know what plan options theyhave, especially if employers aren’t making much effort to signthem up.

Information on a 401(k) may be part of a stack of paperhanded out on their first day, that they don’t read or understand,and ultimately set aside and never think about again.

Now, U.S. Census Bureau researchers have come up withestimates that rely on tax data, which should be morereliable than surveys. Their conclusion: Only about a third ofworkers are saving in a 401(k) or similar tax-deferred retirementplan.

Also, the gap is far wider than expected between the number ofemployers offering retirement plans, and the number of workerssaving in them.

Only 14 percent of employers offer plans

Census researchers Michael Gideon and Joshua Mitchell analyzedW-2 tax records from 2012 to identify 6.2 million unique employersand 155 million individual workers, who held 219 million distinctjobs. This data produced estimates starkly different fromprevious surveys.

For example, previous estimates suggested more than 40 percentof private-sector employers sponsored a retirement plan. Taxrecords uncovered a much bigger pool of small businesses, showingthat, overall, just 14 percent of all employers offer a 401(k)or other defined contribution plan to their workers.

Related: Small companies have a big retirementproblem

Bigger companies are the likeliest to offer 401(k) plans, andsince they employ more people than small firms, skew the overallnumber of U.S. workers who have the option.

Gideon and Mitchell estimate 79 percent of Americans work atplaces that sponsor a 401(k)-style plan. The good news isthat’s more than 20 points higher than previous estimates. The badnews is that just 41 percent of workers at those employers aremaking contributions to such a plan—more than 20 points lower thanprevious estimates.

The combined result of those two numbers is that just 32 percentof American workers are saving anything in a workplace retirementaccount. Four out of five workers are employed by companies thatoffer a 401(k) or similar plan, but most workers aren’t usingthem—either because they’re not eligible or because theyaren’t signing up.

Lawmakers have proposed a variety of ways to get more people tosave. Several states are experimenting with strategies to get everyworker signed up for a retirement account.

But they face serious pushback from the Republican-controlledCongress and the financial industry.

The demise of the pension

Census researchers are still studying the tax data,cross-referencing it with other databases to get a fullerpicture of how Americans are saving.

For example, researchers are using retirement plan filingdocuments to get a better sense of how many workers arestill covered by traditional pensions, also known as defined benefit plans.

Related: Fixing retirement plans? Look to U.K. forideas

According to a Pew Charitable Trusts analysis of survey datareleased Feb. 15, only 10 percent of workers over age 22 have atraditional pension. Just 6 percent of millennials have a pensionwhile 13 percent of baby boomers do.

Not surprisingly, the Census data suggest well-paid workers findit easier to save than the lowest-paid. But income isn’t theonly factor. Eligibility is also a major issue for part-timeworkers and people who change jobs frequently.

Companies often require employees to work for a certain amountof time before they can sign up for a 401(k), andemployers aren’t required to allow part-time workers into aplan until they’ve worked 1,000 hours during the previousyear.

Another problem made clear by the new report is that manyworkers simply don’t know their company 401(k) exists. Workers alsomight never get around to filling out the paperwork, or could beintimidated and confused by the need to make investmentdecisions.

Companies can help solve all those problem by automaticallysigning up eligible workers, and requiring them to opt out if theydon’t want to participate. Doing so has been proven to boostenrollment, but momentum has now stalled for automatic401(k) features.

House moves to block auto-enrollment in state plans

California, Oregon, Illinois, Maryland, andConnecticut have started programs designed to encourageworkers to save. Employers in those states would be required toeither offer a retirement plan, or automatically enroll theirworkers in a state-sponsored individual retirement account.

The states had the blessing of the Obama administration,which issued rules allowing states and even large cities to createportable retirement accounts if they want.

On Feb. 15, however, the U.S. House of Representatives voted to rescindthose rules.

Echoing the arguments of the financial industry, Republicansargued state auto-enrollment plans constitute unfair competition tothe financial industry. If the Republican-controlled U.S. Senateand President Donald Trump also sign off, any state and cityauto-IRA plans would be placed in jeopardy.

Whatever the outcome, any effort to get workers to save forretirement faces a daunting challenge: Can Americans spare themoney?

Student debt and auto loans are at record levels, according toFederal Reserve data released Feb. 16, and overall consumer debt isrising at the fastest pace in three years.

Retirement is an important goal, but many Americans seem to havemore pressing financial concerns.

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