When starting a business, one of the first things you must do is apply for a federal identification number. Then, for each employee you hire, there are several forms they must complete. You can find them all here, available in downloadable PDF format. Adobe Acrobat Reader required.

SS-4, Application for Federal Identification Number — Regardless of your business structure (corporation, partnership or sole proprietor), you'll need a federal identification number to begin. This number is used when paying employment taxes on behalf of your employees. The completed Form SS-4 may be sent to your local IRS office via mail, fax or even called-in.

I-9, Employment Eligibility Verification — Each employee you hire must complete this form and provide supporting documentation. It is your responsibility to keep this form in the employee's file.

W-4, Employee's Withholding Allowance Certificate — Every one of your employees must provide you with a signed W-4 to indicate the number of withholding allowances to use when calculating their Federal Income Taxes. If employees wish to change their allowances, they must submit a new W-4 to you. If a W-4 has not been submitted, employers are required to withhold taxes at the highest rate — single with 0 allowances.

W-5, Earned Income Credit Advance Payment Certificate — Employees who are eligible to receive the Earned Income Credit on their federal tax returns should fill out a W-5, which must be filed with the IRS.