Absolutely, you can modify the EIN from a sole proprietorship to an LLC. The IRS-issued Employer Identification Number (EIN) is solely used for tax filing purposes. It's essential to keep in mind that each party is restricted to one single EIN, so it cannot be shared or distributed among other parties. Moreover, if you incorporate your business as a limited liability company for additional protection of personal assets and finances, then obtaining another new EIN should be done promptly - this will ensure those financial matters are kept separate from one another!