To determine if you need an EIN or if you need a new EIN: https://www.irs.gov/businesses/small-businesses-se...

Businesses need a new EIN when their ownership or structure has changed. Changing the name of your business does not require you to obtain a new EIN, you may wish to visit the Business Name Change page to find out what actions are required if you change the name of your business.

Changing the address of your entity does not require a new EIN.

Changing the structure of the business is changing from a sole proprietor to a corporation or partnership or any of these combinations. Most of the time a new EIN is not needed.

If you are a sole proprietor, you do not need a new EIN if you want to start another sole proprietor business. The EIN is yours just like a Social Security number. This number stays with you forever.