Applying for an EIN Number USA can be done through different methods. Before applying for having your EIN, you need to get all the mandatory details regarding your EIN. If you are running your new business and wanted to file your business loans, file tax returns or want to hire some employees. Employer EIN stands for Employer Identification Number and it is a nine-digit number. IRS allows your business entity to get verified and working. For filing a federal tax return, you need an EIN number.