How to Get an EIN in Connecticut

How to Get an EIN in Connecticut

How to Get an EIN in Connecticut

An Employer Identification Number (EIN) is your business's federal tax ID, issued by the IRS. Whether you're forming an LLC, starting a corporation, or hiring your first employee in Connecticut, an EIN is often your next step after Secretary of the State filing. This guide walks you through the application process, Connecticut-specific requirements, and what comes next.

What Is an EIN and Why You Need One

An EIN is a nine-digit identifier the Internal Revenue Service assigns to businesses, trusts, estates, and certain sole proprietors. It works like a Social Security number for your business. Every business entity, regardless of structure, will eventually need one if they hire employees, operate as a corporation or partnership, file certain tax returns, or maintain a business bank account.

In Connecticut, you register your business entity (LLC, corporation, etc.) with the Secretary of the State. After that registration is accepted, you apply for an EIN from the federal IRS. These are separate processes on separate timelines. Your Secretary of the State filing confirms your business name and structure; your EIN is what the IRS uses to track your federal tax obligations.

When Do You Actually Need an EIN in Connecticut?

You need an EIN if your Connecticut business meets any of these criteria:

  • You have employees (including household workers)
  • You operate as a corporation or partnership
  • You're an LLC taxed as a corporation or S corporation
  • You file employment tax returns, excise tax returns, or alcohol, tobacco, or firearms returns
  • You operate a trust or estate
  • You want a separate business bank account (most banks require one)

Sole proprietors without employees can use their Social Security number for taxes, but most business owners still get an EIN for liability separation and professional credibility.

Materials and Information You'll Need

Before applying, gather these items:

  • Your Social Security number or individual taxpayer identification number (ITIN)
  • Your Connecticut business name and address exactly as registered with the Secretary of the State
  • Your business structure (LLC, corporation, sole proprietorship, partnership, trust)
  • Expected number of employees (even if zero)
  • Principal business activity code (the IRS will ask what your business does)
  • Your responsible party's legal name and date of birth (if it's not you, have that person's info)
  • Mailing address for the business (can be a home address)
  • Phone number where the IRS can reach you

The responsible party is the person with legal authority over the business. For LLCs, this is typically a member; for corporations, it's an officer. Have a copy of your filed Certificate of Organization or Certificate of Incorporation handy, though you won't submit it with the EIN application.

Step-by-Step: How to Get an EIN

Step 1: Apply Online (Fastest Method)

The fastest and easiest way is applying directly on the IRS website at https://www.irs.gov/ein-online. You can apply Monday through Friday, 7 a.m. to 10 p.m. ET. The online application takes 10 to 20 minutes. You'll receive your EIN immediately upon completion and can print a confirmation. There is no fee.

You must be a U.S. citizen, resident alien, or sole proprietor with a U.S. Social Security number to apply online. If you've recently received an EIN and closed the business, the IRS will reject a new application from the same SSN. Wait at least one business day before reapplying.

Step 2: Apply by Mail (If Online Isn't an Option)

If you cannot apply online (for example, if you're a foreign entity or entity without a U.S. SSN), file Form SS-4 by mail. You can download it free from https://www.irs.gov/forms or order it by phone at 1-800-829-3676.

Mail the completed Form SS-4 to the Internal Revenue Service Center serving Connecticut. As of 2026, Connecticut falls under the Andover, Massachusetts IRS Service Center. Send it to:

Internal Revenue Service
Attn: EIN Operation
Andover, MA 05501

Processing time by mail is typically 4 to 6 weeks, though it can occasionally take longer. You will not receive your EIN immediately.

Step 3: Verify Your Information Before Submitting

Whether applying online or by mail, double-check these details before you hit submit or seal the envelope:

  • Your business name must match your Secretary of the State filing exactly
  • The business start date (when you expect to begin operations) is accurate
  • The principal business activity is correct (this affects some tax treatment)
  • Your responsible party's name is spelled correctly and the date of birth is accurate
  • Your phone number is one you'll answer, or include a trusted contact's number

A mismatch between your Secretary of the State record and your EIN application can delay processing or cause mail delivery issues. Verify the exact name and address from your filed Certificate of Organization or Incorporation.

Step 4: Receive Your EIN (Immediately or in 4 to 6 Weeks)

Online applicants get the EIN on screen and via email within minutes. Print and save the confirmation. If you applied by mail, the IRS will send a notice (Form SS-4) in the mail with your EIN assigned. Watch for that letter; you'll need the EIN for your Connecticut tax accounts and bank account setup.

Do not apply a second time while waiting for a mailed response. Duplicate applications cause delays.

What Happens After You Get Your EIN

Register for Connecticut Tax Accounts

Once you have your EIN, you may need to register with the Connecticut Department of Revenue Services (DRS) depending on your business type. Visit https://portal.ct.gov/drs to explore registration requirements.

Most Connecticut businesses that sell taxable goods or services must register for a Sales and Use Tax Permit. The permit registration fee is $100. Register online at https://portal.ct.gov/drs/sales-tax/tax-information. You cannot collect sales tax legally without a permit, and failure to register is subject to penalties.

If you hire employees, you also need a Connecticut Employer Account Number (CONN). Register through the DRS or contact them directly. This is separate from your federal EIN and is used for state unemployment insurance and wage withholding taxes.

Open a Business Bank Account

Banks require an EIN (or your SSN if you're a sole proprietor) to open a business checking account. Bring your EIN confirmation letter and a government-issued ID to the bank. Separating business and personal finances from day one protects your liability protection and makes tax time much simpler.

Set Up Federal Payroll Tax Accounts (If You Have Employees)

If you have employees, you must set up a federal payroll account (Form 941 account) with the IRS. Your EIN is linked to this automatically. You'll make federal withholding deposits and file quarterly or monthly payroll tax returns.

Tips for a Smooth EIN Application

  • Apply online first. You get the number immediately, with zero processing time. Mail applications can languish for weeks, and mailed confirmations sometimes go astray.
  • Know your principal business activity code before you start. The IRS categorizes businesses by activity. If you're unsure, search the IRS's Activity Code list (found on their Form SS-4 instructions). Picking the closest match is fine; you can update it later if needed.
  • Complete your Secretary of the State filing first. You need a business name and structure finalized. Applying for an EIN before filing your LLC or corporation with the Secretary of the State can cause mismatches and delays.
  • Use a consistent address. Whether home or office, use the same address on your Secretary of the State filing and your EIN application. Mismatches trigger IRS follow-up calls or letters.
  • Keep your confirmation for at least three years. You'll need to reference your EIN on tax returns, payroll reports, banking forms, and vendor accounts. Save the confirmation email or letter in a safe place.
  • Use your EIN, not your SSN, on all business documents. On invoices, business tax returns, employment filings, and vendor forms, always cite your EIN, not your personal Social Security number. This keeps personal and business finances clearly separate.

Common Mistakes to Avoid

  • Applying before your Secretary of the State filing is accepted. The IRS needs to verify your business name exists. Wait until your Certificate of Organization or Incorporation is officially filed and accepted.
  • Typing the business name differently on the EIN form than on your Secretary of the State filing. "ABC Consulting LLC" and "ABC Consulting Limited Liability Company" will cause flags. Match it exactly.
  • Submitting multiple applications at once. If you apply online and then mail Form SS-4, the IRS assigns two EINs. This creates accounting confusion and extra work to consolidate. Pick one method and stick with it.
  • Using a temporary address." Avoid using a mail drop, UPS box, or temporary address as your principal business location. The IRS may reject the application or contact you for verification.
  • Forgetting to register for Connecticut sales tax. An EIN does not automatically register you for Connecticut tax accounts. You must complete that separately, and every business collecting sales tax must have a permit. Operating without one is a violation.
  • Not saving your EIN confirmation. If you apply online, print and email the confirmation to yourself immediately. Browser crashes, computer failures, and accidental deletions happen. Losing your confirmation complicates future filings.

Expected Timeline

Here's what to expect from start to full setup:

  • Days 1 to 5: File Certificate of Organization or Incorporation with Connecticut Secretary of the State. Online filing is accepted within 24 hours; mail filings take several business days.
  • Days 6 to 7: Once your filing is accepted, apply for your EIN online (immediate) or by mail (4 to 6 weeks).
  • Days 8 to 14: Register for Connecticut sales tax permit and state employer account number if applicable.
  • Days 15 to 21: Open a business bank account with your EIN.

Online EIN applicants can be fully set up and operational within 1 to 2 weeks of filing their entity. Those using mail will wait longer for the IRS confirmation, though they can use the temporary EIN assigned during online verification or via phone application (call the IRS Business and Specialty Tax Line at 1-800-829-4933).

Important Disclaimer

This article provides informational guidance on obtaining an EIN for Connecticut businesses and is not legal or tax advice. EIN requirements vary by business structure, ownership, and industry. Consult a licensed attorney or certified public accountant (CPA) to confirm what registrations and tax accounts your specific business requires. The Connecticut Small Business Development Center (CTSBDC) at https://ctsbdc.uconn.edu/ also offers free consulting and can guide you through the full startup process.

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