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There's a mystery brewing at the Social Security Administration, revolving around the agency's so-called suspense file. Granted, this "S-file" enigma may not be as captivating as the nefarious X-File plots that agents Scully and Mulder unravel each week on television. But the consequences could be financially chilling for tens of millions of Americans. This suspense file, you see, contains the Social Security Administration's records of more than $200 billion earned by American workers that the agency hasn't been able to match with their rightful owners. If some of these earnings belong to you, you could get a smaller monthly Social Security check than you deserve--or miss out on benefits entirely. "The workers in my district who are caught up in this debacle are owed $1,000 on average in back Social Security payments," says Rep. George Brown (D-Calif.). "Some are owed far more."

To get a clue whether this problem affects you, think back to all the jobs you've ever held. Did you always use the same version of your name when you filled out payroll forms? Ever use Bill instead of William or insert your middle initial or middle name? Did you stick with your maiden name, even after you married? Also, did you ever hold a job in the restaurant, hotel or health-care industry?

Any one of these seemingly innocuous moves raises the odds that you may be in for a boost in the size of your Social Security checks--if you take action. Here's why: The Social Security Administration gets more than 240 million W-2 forms and other wage reports annually from employers and the self-employed, covering $3.2 trillion in earnings. The agency then credits workers' Social Security accounts for those earnings by matching the names and Social Security numbers furnished by employers to those in its files. Each year, however, about 10% of these wage reports--22 million in 1995--get exiled to the dreaded suspense file because of a mismatch in name or Social Security number. The agency periodically runs these orphaned earnings statements through a battery of tests to rescue them from the S-file. But 1.5% to 2% of the reports never find their way out of this black hole. Industries like those mentioned earlier are responsible for half of the mistakes, largely because of payroll-record errors stemming from their high job turnover. Name changes--especially after marrying or divorcing--also account for a large portion of the erroneous reports, although the Social Security Administration doesn't have figures on how many errors result from women switching from or back to their maiden names.

Workers whose wage statements wind up in the S-file may get shortchanged on their Social Security benefits. A 65-year-old retiree unfortunate enough to have just one year's peak earnings of $45,000 disappear into the suspense quagmire, for example, could lose $42 a month in Social Security payments--or almost $10,000 over a projected 19-year retirement. Worst-case scenario: You worked for 10 years, but Social Security has records for only nine. Then you might get no Social Security checks, since you generally must work at least a decade to qualify for benefits.

The Inspector General (IG) of the Social Security Administration expects to deliver a report on its investigation of the suspense file problem to Acting Social Security Commissioner John J. Callahan in October. Rep. Brown has also introduced legislation to develop ways of crediting workers for their S-file earnings, although he wants to see the IG's report before pushing his bill through Congress.

To prevent your earnings from being gripped by suspense, follow these three tips:

--Order your free Social Security Personal Earnings and Benefit Estimate Statement (PEBES) by calling 800-772-1213. This document notes all your earnings that have been reported to Social Security year by year. If it's not accurate--say, you see a zero listed on the statement for a year that you actually worked--gather records such as W-2s, tax forms and salary stubs that can document your employment. Then call the same Social Security toll-free number and talk to a representative about correcting your earnings record.

--Phone Social Security if you change your name for any reason, including taking your spouse's name after marriage. After you've called the toll-free number above and reported the name change, phone again in a month and request a copy of your PEBES form. If it doesn't contain your entire earnings history under both your names, notify Social Security again.

--Don't change your name at work. Make sure that the name that appears on your employment records, such as W-2 forms, is identical to that on your Social Security card. Never use a nickname on those job records, unless it's also on the Social Security card.