Guide

Third Party Designee on SS-4 (2026) Guide

The third party designee on Form SS-4 Line 18 authorizes someone to receive the EIN on your behalf. ein.so serves as third party designee for our clients.

The third party designee on Form SS-4 (Line 18) is the person or organization authorized to receive the EIN and discuss the application with the IRS on your behalf. When you use ein.so, we serve as your third party designee. This allows us to receive your EIN directly and deliver it to you.

What Is It

Third Party Designee Explained

| Detail | Information | |--------|------------| | Location on SS-4 | Line 18 | | Purpose | Authorizes someone to receive EIN on your behalf | | Required? | No (optional) | | Who uses it | EIN services, attorneys, CPAs | | ein.so clients | We are listed as designee |

How It Works

When you designate a third party on Line 18:

The IRS sends the EIN to the designee (not directly to you)
The designee can discuss your application with the IRS
The designee forwards your EIN to you
Authorization is limited to the EIN application only

When to Use

When to Use a Third Party Designee

Using ein.so: We handle everything — list us as designee
Using a CPA: Your accountant can be designee
Using an attorney: Your lawyer can be designee
DIY filing: Leave Line 18 blank (IRS sends EIN directly to you)

The responsible party (Line 7a) is different from the third party designee (Line 18). The responsible party is the individual who controls the entity. The designee is who receives the EIN on your behalf.

SS-4 form guide — Complete form instructions
Responsible party — Line 7a guidance
EIN by fax — Fax submission process

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Frequently Asked Questions

What is a third party designee on SS-4?

A person or organization authorized on Line 18 of Form SS-4 to receive the EIN and discuss the application with the IRS on your behalf.

Is third party designee required?

No. It is optional. If you leave Line 18 blank, the IRS sends the EIN directly to you.

Who should I list as designee?

If using ein.so, list us. If using a CPA or attorney, list them. If filing yourself, leave blank.

Is designee the same as responsible party?

No. Responsible party (Line 7a) is the individual who controls the entity. Designee (Line 18) is who receives the EIN.

Can I change the designee later?

The designee authorization is only for the EIN application. It does not carry over to other IRS matters.

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