When you have your own business and want to expand it then you have to apply for an EIN number completely. The EIN number tells the identity fr a particular business you have and running it. Moreover, an EIN certificate is required when you are running your business. It is all easy to go with making the EIN number as well to hire employees and file for business taxes. In addition to this, there is a need to fill in the SS4 forms while applying EIN from different methods.