The Tax ID you establish during your account setup process cannot be changed once your account is created. Please be careful to enter the correct Tax ID (EIN or SSN) when establishing your account. If you are an Individual Provider, you must enter your SSN as your primary tax identifier. You will have the opportunity to add your EIN (if applicable) later in the enrollment/re-enrollment process. If you are a Group, Institution, or Facility you should enter your EIN. However, you may use your SSN as your primary Tax Identifier if you do not have an EIN. Existing providers that are intending to do a re-enrollment or an update will be required to enter additional identifying information before establishing an account. Once the Tax ID is established for your account, you will be able to enroll, re-enroll, and update other providers that may use this same Tax ID.