How to Get an EIN for Your Co-Founder Pair Business in Arizona (2026)

Starting a business with a co-founder in Arizona is an exciting venture. An Employer Identification Number (EIN) is crucial for your co-founder pair business in Arizona to handle taxes, hiring, and opening a bank account. This guide will walk you through obtaining an EIN in 2026, ensuring your Arizona business is set up for success. Lovie can streamline this entire process, providing AI-powered assistance for a seamless formation experience.

What is an EIN?

An Employer Identification Number (EIN) is a unique nine-digit number assigned by the IRS to identify your business entity. Think of it as a Social Security number for your business. It's required for various business activities, including paying federal taxes, hiring employees, and opening a business bank account. For co-founder businesses, an EIN is essential for proper legal and financial operations.

How to Apply for an EIN

  1. Determine Eligibility: Ensure your co-founder business structure (LLC, partnership, or corporation) requires an EIN. Most Arizona businesses with more than one member or those planning to hire employees will need one.
  2. Choose a Responsible Party: Designate a 'responsible party' – usually one of the co-founders – who will control, manage, or direct the entity and the disposition of its funds and assets. This person must have a valid Taxpayer Identification Number (SSN or ITIN).
  3. Complete the EIN Application (Form SS-4): Access the IRS website and complete Form SS-4, the Application for Employer Identification Number. You can apply online, by fax, or by mail.
  4. Provide Business Information: You'll need to provide details about your Arizona business, including its legal name, address, business activity, and the number of members (co-founders).
  5. Submit the Application: If applying online, submit the completed Form SS-4 electronically. If applying by fax or mail, follow the IRS instructions for submission.
  6. Receive and Store Your EIN: Upon successful application, you'll receive your EIN from the IRS. This will be a PDF document if applied online. Keep this document in a safe and accessible location.

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