The IRS receives copies of all W-2s and 1099s that taxpayers get. The agency will not necessarily question taxpayers who claim more income than their forms show, but it will have questions for anyone who claims less. Not claiming the wages you earned at a company that went out of business and did not send you a W-2 form. The IRS can send you a blank substitute W-2 to use with your own figures. Not knowing whether your unemployment compensation is taxable.
Unemployment compensation is indeed taxable.
Overpaying your Social Security deductible if you had more than one job in a year. If you worked for two or more employers during 2000, you may have had too much Social Security tax withheld. Not knowing if your dividends are a return of capital and therefore not fully taxable. A return of capital is a return of your original investment and not taxable unless the return exceeds your investment. Incorrectly claiming for spousal support.