Not easy to get info. Here are some ideas: 1) If you have time, contact them by letter, inform them of their problem, & ask for an updated W-2. 2) Increase your persistence in calling the company. Sometimes they staff their phones much less frequently at certain times. Try some other phone numbers and call them diligently too. Also, go to the website and make sure you have their best contact numbers. 3) Search the web for "Form-10K" AND "the company name". This search may find this form that is an SEC business listing, containing their EIN. 4) Last Resort: search the web for manufacturer directories and business directories that list the company & have EIN. Use "off time" wisely.