Now that the Obama Administration has decided to zero in on employers with massive numbers of I-9 audits (652 in one day!), let me provide you with a few tips which I've gleaned from assisting employers survive such audits over the past 20 years:
Tip #1 - Make sure that each new hire completes Section 1 of the form on the first day of employment. If the employee's information is incomplete, it is you who pays the fine, so proofread this section very carefully.
Tip #2 - Complete Section 2 of the form by the employee's third day of employment. Show the employee the back of the form, and have him/her show you either one List A document (ID and Employment Authorization) or one List B document (ID) and one List C (Employment Authorization) document. Do not request specific documents or additional documents.
Tip #3 - Keep your I-9 forms separate from employee personnel files. Otherwise, you will have a lot of sorting to do if you receive a Notice of Inspection. The forms must be retained for three years after the employee is hired or one year after his employment ceases, whichever is later. Keep the forms of active employees separate from those of former employees. Purge the latter on a regular basis.
Tip #4 - Create a tickler system for employees who check the box in Section 1 which indicates that they possess only temporary employment authorization. Send them notices well in advance of the termination of their work permits advising them of the need to update their I-9 forms. Remember that certain types of work status are extended simply by submitting an application for an extension to the USCIS. Never update the forms of U.S. citzens or permanent residents, even though "green cards" all have expiration dates.
Tip #5 - Protect yourself from violating the "antidiscrimination" provisions of the law by treating employees who may look or sound "foreign" to you the same as employees who are U.S. citizens.
Tip #6 - Carefully read USCIS' "Handbook for Employers" which we link to from our "Employers' Immigration Guide" at http://shusterman.com/toc-emp.html#9
Tip #7 - Have an attorney who has expertise in I-9 laws and procedures to review all of your I-9 forms at least once each year. The amount that you spend will be a tiny fraction of what you might be fined by the government if you are audited.