Last reviewed October 7, 2026 · By the NYBACS advisory team
Short answer
An EIN (Employer Identification Number) is the nine-digit federal tax ID the IRS assigns to a business, written as XX-XXXXXXX. A US company needs one to file federal returns such as Form 1120, Form 1065 or Form 5472, open a business bank account, run payroll and give clients a Form W-9. Despite the name, an EIN is needed even with no employees, and a foreign-owned single-member LLC must have its own.
Key takeaways
- An EIN is assigned once to an entity and is not reissued to anyone else, even after the business closes.
- The IRS confirms a new EIN with notice CP 575; a lost confirmation is replaced on request with Letter 147C, and eligible Business Tax Account users can download a digital CP 575.
- A single-member LLC owned by a non-US person needs its own EIN because it must file Form 5472.
- An EIN is federal only: state sales tax, payroll withholding and unemployment insurance accounts are registered separately.
- Changes to the business mailing address, location or responsible party are reported on Form 8822-B, and a responsible party change within 60 days.
What the number is and what it identifies
An EIN is the IRS's account number for a business. Every federal return, payroll filing and information return the company submits is matched to it, and every notice the IRS sends refers to it. It also links the company to a responsible party — the individual who ultimately owns or controls the entity — whom the IRS records when the number is issued.
The name is historical. The IRS originally used it for employers, but it now serves as the tax identification number for corporations, partnerships, LLCs, trusts and estates, whether or not they have any staff.
Where a US company uses its EIN
| Situation | Why the EIN is needed | What is usually requested |
|---|---|---|
| Opening a business bank account | Banks verify the company's tax identity | CP 575 or Letter 147C |
| Payment processors and marketplaces | Platforms match legal name and EIN with IRS records | Name and EIN exactly as the IRS holds them |
| Federal returns | Form 1120, Form 1065, or pro forma Form 1120 with Form 5472 | EIN on every page |
| Hiring employees | Payroll tax deposits, Form 941, Forms W-2 | EIN plus state payroll accounts |
| Getting paid by US clients | Clients collect Form W-9 and may issue Forms 1099 | EIN and legal name |
| State registrations | Sales tax, payroll and foreign qualification applications ask for it | EIN letter |
In practice the EIN is the first thing almost every counterparty asks for after the formation certificate.
One point that surprises foreign owners: a company formed in the US is a US person for tax-form purposes even if every owner lives abroad. It gives clients and platforms a Form W-9 with its EIN, not a Form W-8BEN-E, and the foreign-owner details are reported elsewhere, such as on Form 5472.
EIN versus SSN, ITIN and state tax numbers
- SSN identifies a US individual for tax and social security purposes. Non-US founders usually do not have one.
- ITIN identifies an individual who has a US tax filing need but cannot get an SSN — for example a foreign owner who must file Form 1040-NR. It belongs to the person, not the company.
- EIN identifies the entity. A company has one EIN regardless of how many owners it has.
- State tax IDs are issued by each state's tax or labor department for sales tax, withholding and unemployment insurance. Having an EIN does not register you with any state.
Mixing these up is common: a foreign owner's ITIN should never appear where the company's EIN belongs, such as on the company's W-9.
Which entities need their own EIN
Corporations and multi-member LLCs always need one. A single-member LLC owned by a US individual with no employees can sometimes use its owner's number for income tax, but a single-member LLC owned by a non-US person must obtain its own EIN because it files Form 5472 in its own name. Banks will require it in any case.
A new EIN is generally needed when a new legal entity is created — a new subsidiary, or a sole proprietorship that incorporates. An existing LLC that elects to be taxed as a corporation keeps its EIN. Applying for a second EIN for the same company, for example because a first application seemed slow, creates duplicate IRS accounts that have to be untangled later.
Keeping EIN records in order
Store the CP 575 notice with the formation certificate; it is the document banks and processors most often ask to see. If it is lost, request Letter 147C from the IRS or, if eligible, download a digital CP 575 from the IRS Business Tax Account.
Use Form 8822-B whenever the business mailing address, business location or responsible party changes, so IRS notices keep reaching someone who can act on them. An EIN is never cancelled; when a company winds up, the IRS business account is closed by letter once final returns are filed.
Common mistakes to avoid
- Treating the EIN as optional because the company has no employees.
- Putting the foreign owner's ITIN or home-country tax number on the company's W-9 or bank forms instead of the company's EIN.
- Losing the CP 575 notice and having to request a Letter 147C in the middle of bank onboarding.
- Applying again after a slow fax response and ending up with two EINs for one company.
- Not filing Form 8822-B when the responsible party or mailing address changes, so IRS notices go unanswered.
NYBACS 360° support
How NYBACS helps
- Obtains the EIN for foreign-owned companies through Form SS-4, including by fax as your third-party designee.
- Requests Letter 147C when the original CP 575 is missing and a bank or processor needs proof of the number.
- Prepares and files Form 8822-B when your responsible party or address changes.
- Uses the EIN to set up state registrations and your federal filing calendar so nothing is registered twice.
Frequently Asked Questions
Does an EIN expire if the company is inactive?
No. The number stays assigned to the entity permanently. What changes is whether filing obligations continue, which depends on the entity's status and activity, not on the EIN.
Can I apply for an EIN before the company is formed?
You should wait until the state has accepted the formation filing. Form SS-4 asks for the legal name exactly as it appears on the charter and the date the business started, and applying early risks a mismatch.
Does having an EIN mean the company owes US tax?
No. The EIN only identifies the company. Whether it owes tax or must file depends on its entity type, ownership and activities — although a foreign-owned single-member LLC almost always has at least a Form 5472 filing.
Is it safe to share our EIN?
Clients, banks and payment platforms legitimately need it, so it cannot be kept secret. Share it on official forms such as the W-9, but avoid publishing it on websites, as it can be misused in business identity fraud.
