How long it takes to receive your federal tax ID number is based on two things: how you filed for it and whether there were any errors in your application. First, you can file for an EIN/Tax ID online, through mail, through fax, or through phone. If you file online (the best method), you should get it within an hour. If you file through mail, it may be four to six weeks. Fax can take four to five days, and phone may take a few hours, but is highly variable depending on how busy they are and whether you can connect to someone.
More importantly, it will also be based on whether there were errors in the application. If there were, you need to start the process again. It’s often beneficial to go through a tax ID service, because they will check your application first, and will let you know if there have been any errors. Otherwise you could find yourself having to resubmit your application, extending the waiting time.