A company can use a single EIN across multiple units with multiple fictitious names. You can have multiple DBA under one sole proprietorship, or multiple business names under one corporation. Your DBAs are just your business nicknames, and therefore, you won’t have a separate EIN for a DBA. Whether you’re required to have one depends on how your business is organized and what kind of taxes it pays.
An EIN is a unique Tax Identification Number (TIN) that the IRS uses to identify your business or organization. Fictitious names are a state matter, most states require businesses to register their DBAs. You can file all government forms yourself paying fees only if any apply.
When you change your business name, you submit an EIN name change. Each business entity can have only one EIN.
However, just because it’s possible to operate several different types of businesses under one company doesn’t mean you should. If you have multiple businesses that are taxed differently, such as a corporation and an LLC, they’ll require separate EINs. Many bankers would request an EIN regardless.