If you’re required to file a business tax return, you’re going to need an employer identification number. Taxpayers who use EINs include employers, sole proprietors, corporations, partnerships, non-profit associations, government agencies, and other business entities.

You can apply for an EIN online by visiting IRS.gov/EIN. You can also apply by fax or by mail. Just check the instructions for Form SS-4 for the details about these methods. Remember that international applicants can only apply by mail, phone, or fax.

On the EIN application, you’ll need to include the name of the person in charge of the entity and its assets. This person is called the responsible party. If you already have an EIN and the organization or ownership of your business changes, you may need to apply for a new number. If your tax return is due and you haven’t received your EIN, write “Applied for” and the date that you applied for it in the space shown for the number.

For more information, visit IRS.gov/EIN.