Please explain what you mean. And do you mean EIN? What are you trying to do?
an efin is for professionals who efile returns for clients. a PTIN is also required. you can not use Turbotax since you can't sign the return - a federal law violation if compensated - unless mailed inhttps://www.irs.gov/e-file-providers/faqs-about-electronic-filing-identification-numbers-efin