No, for federal income tax purposes a sole member LLC is normally considered a "disregarded entity." Unless you hire employees, you can use your social security number for all purposes.
However, for security reasons, you may want to get Federal Tax Identification Number (also known as Employer Identification Number or Employer ID Number) in order to reduce the number of people who have access to your social security number. In addition, it is a good idea to keep the LLC’s business strictly separate from your personal affairs in order to protect the LLC’s limited liability shield. Having your SSN on all of your LLC’s bank accounts and other documents could give the impression that your personal affairs and your business are not separate.
You can get your Federal Tax Identification Number and more information here.
