When taxpayers and tax professionals e-file income tax returns in Revenue Online or other tax software, they should be sure the employer’s Federal Employer Identification Number (FEIN) is carefully entered and take a minute to review the numbers . The FEIN should be on the W-2 or 1099 statements. The Colorado Department of Revenue verifies the FEINs to ensure the employer has paid the taxpayer’s withholding tax. When there is no FEIN with the income tax filing or the FEIN is incorrect, the taxpayer will not get credit for income taxes already paid through withholding. Carefully review your e-file entries to ensure smooth return (and refund) processing.