An EIN (Employer Identification Number) is essentially a Social Security number for your business, issued by the IRS. Most new LLCs need one, but exactly when and why trips people up during formation.
When an EIN is required
Any LLC with employees, more than one member, or that elects to be taxed as a corporation needs an EIN. Even single-member LLCs with no employees typically need one to open a business bank account, since most banks won't let you use your personal Social Security number for a business account.
It has to line up with your formation documents
An EIN application asks for details that need to match your formation documents exactly — legal business name, entity type, and responsible party. A mismatch between your operating agreement and your EIN application is a common source of delays and banking headaches later.
Timing relative to formation
You generally need your LLC to be officially formed with the state before applying for an EIN, since the application requires your approved entity name and formation date. Applying too early, with the wrong information, can create a mismatch that has to be corrected with the IRS.
Getting your formation paperwork sequenced correctly
Getting your operating agreement, articles of organization, and EIN application aligned and filed in the right order avoids the back-and-forth of fixing mismatched business details after the fact — a small thing that causes outsized delays when you're trying to open accounts and start operating.