Form SS-4: How Your Business Applies for an EIN

What Is an EIN and Why Does Your Business Need One?

An EIN functions as the business equivalent of a Social Security Number. It identifies the entity on tax filings, payroll submissions, bank account applications, and business license paperwork. Corporations, partnerships, LLCs, and any business with employees are required to have one.

Sole proprietors without employees can technically use their personal SSN for tax purposes, but obtaining an EIN is strongly advisable. It keeps your Social Security Number off vendor contracts, 1099 forms, and banking applications, which reduces exposure to identity theft. It also makes it easier to open a dedicated business bank account and establish business credit under the entity rather than the individual.

Who Needs to File Form SS-4?

Any business entity that needs an EIN files Form SS-4. That includes corporations, partnerships, LLCs of all types, sole proprietors with employees, and estates and trusts. Single-member LLCs with no employees aren't strictly required to have an EIN for federal tax purposes, since income flows through to the owner's SSN by default, but an EIN is recommended for the banking and privacy reasons above.

Foreign-owned US entities have a mandatory EIN requirement. A foreign-owned single-member LLC subject to Form 5472 reporting must obtain an EIN regardless of whether it has employees or files a tax return in the traditional sense.

How to Apply for an EIN: Online vs. Fax vs. Mail

The online application is the fastest option by far and issues the EIN immediately upon completion. It's available only to businesses with a US address and a responsible party who has a US Social Security Number or Individual Taxpayer Identification Number. The entire process takes about 15 minutes.

Fax applications are processed in approximately four business days. Mail applications take four to five weeks. Both fax and mail require completing Form SS-4 in full and submitting it to the appropriate IRS address based on the applicant's location. International applicants without a US SSN or ITIN have no access to the online system and must go through fax or mail.

Form SS-4 for Foreign-Owned Businesses and International Applicants

Foreign nationals forming US LLCs or corporations who don't have a US SSN or ITIN cannot use the online EIN application. They must complete Form SS-4 and submit it by fax to the IRS EIN Operation line or by mail to the Cincinnati Service Center. A third-party designee, such as an attorney, accountant, or formation agent, can file on the business's behalf if authorized in the form's designee section.

Processing times for international fax applications are typically four to eight weeks, though delays beyond that are not uncommon. This timeline is the most important practical consideration for foreign founders opening a US business: the EIN application should be submitted immediately after entity formation, because most US business bank accounts require an EIN to open. Waiting until the EIN arrives to begin the banking process adds weeks to the timeline before the business can receive or send payments through a US account.

What Information Is Required on Form SS-4?

The form collects identifying and organizational information about the entity. You'll need the legal name of the business, any trade name used, the name and SSN or ITIN of the responsible party (the individual who controls or manages the entity), the business address, the entity type, the reason for applying, the date the business started or was acquired, the principal business activity, and the expected number of employees in the next 12 months. For entities with foreign responsible parties, the form also requires the country of citizenship and foreign address.

How Slash Helps New Businesses Get Banking-Ready from Day One

An EIN from Form SS-4 is the prerequisite for opening a business bank account, and getting a bank account open is what allows the business to actually operate. Slash's business banking is built for businesses at every stage of formation, including new LLCs, recently formed corporations, and foreign-owned US entities working through the EIN process.

Once the EIN is in hand, opening a Slash business account is straightforward, giving new businesses the dedicated banking infrastructure they need from the start rather than running early transactions through personal accounts while waiting for the pieces to come together.