You think the government's always right? Think again. Mistakes in Social Security calculations are surprisingly common.

Government watch groups estimate that the Social Security Administration (SSA) makes mistakes on at least 3 percent of the total official earnings records it keeps.

The best way to keep an eye on your personal Social Security records is to carefully review your yearly Social Security statement, and dont be surprised if you uncover an error.

Heres what you should know.

Earnings Errors

Social Security benefits are based on your 35 highest-earning years as reported to the government by your employers. If an employer has given the government incorrect salary data or if the government has erred in recording the information, you want to get it corrected as quickly as possible.Otherwise you may not get the full amount youre entitled to when you retire.

So, when you receive your annual Social Security statement, take the time to compare the earnings listed in the statement with income listed on W-2 forms in your tax records. And if you spot a discrepancy, follow these steps:

Call your nearest Social Security office (see www.ssa.gov/locator or call 800-772-1213 to get the number) to report the error. Some corrections can be made over the phone. However you may need to schedule an appointment and go in with copies of your W-2 forms or tax returns to prove the mistake, or you can mail it in.

If you suspect a discrepancy but dont have backup records, the SSA may be able to use your employment information to search its records and correct mistakes. If the SSA cant locate your records, youll need to contact the employer to obtain a copy of your W-2 for the year in question.

Once your earnings record is corrected, SSA will send you a confirming letter. If you dont receive the confirmation within three months, contact SSA again. And double-check the correction by making sure it appears on next years statement.

If corrections arent made on the next statement you receive, start an appeals process (see www.ssa.gov/pubs/10041.html).

Note: SSA statements are mailed annually (about three months before your birthday) to everyone age 25 and over who is not already receiving Social Security benefits. If youre not receiving yours, see www.ssa.gov/mystatement.

Other Mistakes

Earnings miscalculations can also happen if the SSA didnt have your correct mailing address. If you dont receive your annual statement, thats a tip-off.

If there is a mistake, contact the IRS (SSA depends on the IRS for addresses) at 800-829-3676 and ask them to mail you the Change of Address form 8822, or print it off at www.irs.gov/pub/irs-pdf/f8822.pdf, fill it out and mail it back to the address on the form.

Two other factors that can cause mistakes are if you changed your name following a marriage or divorce, or if your date of birth in SSA records isnt the same as it appears in IRS files. Double check your SSA statement for these possible mishaps and make sure your earnings data matches the amounts on your W-2 forms.

And whenever you change your name, or if you notice a birth date error call the SSA (800-772-1213) and ask for Form SS-5, Application for a Social Security Card, and submit it with the correct information. The form can also be downloaded at www.ssa.gov/online/ss-5.html.

Calculation Errors

Even when all the earnings data is correct, the SSA occasionally errs in calculating benefits.

You can double check their calculations by using SSAs formula found at www.socialsecurity.gov, however the math is rather complex.

If you think your benefits have been miscalculated, point it out to your local SSA office and ask them to recalculate. If they do find an error, make sure you receive a confirming letter and that the correction appears on next years statement. If youre already receiving benefits, the SSA will reimburse you for the amount of the error.

---

Jim Miller is a contributor to the NBC Today show and author of The Savvy Senior books.