Quick verdict
For most small businesses, the EIN from the IRS is the single most important corporate number, and it costs nothing to obtain. As your business grows into state-level sales, employees, or government contracts, layer in the state tax ID, DUNS, and SAM UEI in that order. The LEI is a niche requirement for financially regulated entities. Start with what your current business stage demands, document everything, and add r
EIN (Employer Identification Number) - Best for Federal Compliance
The EIN is the foundation of any US business identity. Issued by the IRS in minutes through the online application portal, it functions as a Social Security number for your business and is required for opening a business checking account, filing federal taxes, running payroll, and forming an LLC or corporation. Even single-member LLCs with no employees benefit from having one because it separates your personal SSN from vendor W-9 forms. The IRS application is free, instant during business hours, and straightforward. This is the first number every US business should secure before doing anything else.
Check price on Amazon →Which corporate number do you actually need? Here are five identifiers that unlock bank accounts, vendor contracts, and tax compliance for your business.
Getting a corporate number sounds like a bureaucratic checkbox, but the right identifier for your business stage determines how fast you can open bank accounts, land vendor contracts, file taxes without penalty, and qualify for government grants. The five identifiers below cover the most commonly needed registration numbers for US-based businesses, from solo freelancers to incorporated entities scaling toward federal contracting.
| Business Number | Issuing Body | Primary Use |
|---|---|---|
|
ⓘ We may earn a commission from qualifying purchases made through links on this page, at no extra cost to you.
|
IRS | Federal tax, banking, payroll |
| DUNS Number | Dun & Bradstreet | Credit, federal contracts |
| State Tax ID | State revenue agency | State tax filings, sales tax |
| LEI (Legal Entity Identifier) | GLEIF-accredited issuers | Financial transactions, reporting |
| SAM UEI | GSA / SAM.gov | Federal government contracting |
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EIN (Employer Identification Number) - Best for Federal Compliance
The EIN is the foundation of any US business identity. Issued by the IRS in minutes through the online application portal, it functions as a Social Security number for your business and is required for opening a business checking account, filing federal taxes, running payroll, and forming an LLC or corporation. Even single-member LLCs with no employees benefit from having one because it separates your personal SSN from vendor W-9 forms. The IRS application is free, instant during business hours, and straightforward. This is the first number every US business should secure before doing anything else.
DUNS Number - Best for Credit and Federal Contracts
The DUNS (Data Universal Numbering System) number from Dun & Bradstreet is a nine-digit identifier that establishes your business credit profile. It is required for most federal government contracts and grants, and many large enterprise vendors check it before extending net-30 payment terms. The standard application is free and takes up to 30 business days. If you are bidding on a federal contract, the DUNS feeds into your SAM.gov registration. A business with an active DUNS and documented payment history builds a Paydex score, which functions like a personal credit score but for your company.
State Tax ID Number - Best for Sales Tax and State Payroll
If you sell taxable goods or services, or if you have employees, your state requires a separate tax identification number distinct from your EIN. The application is handled through your state's department of revenue or taxation, is typically free, and can usually be completed online within a week. Without it, you cannot legally collect sales tax, remit it to the state, or run payroll for in-state employees. Some states also require a separate employer account number for unemployment insurance contributions. Check your specific state's requirements, as the naming and process vary.
LEI (Legal Entity Identifier) - Best for Financial Reporting
The Legal Entity Identifier is a 20-character alphanumeric code required for businesses that trade financial instruments, report under MiFID II, or deal in securities markets. Issued through GLEIF-accredited providers, it costs between and annually depending on the registrar. If your business does not operate in securities or derivatives, you likely do not need an LEI. But for fund managers, broker-dealers, and companies with cross-border financial reporting obligations, an LEI is a compliance requirement, not optional. Annual renewal is required to maintain active status.
SAM UEI - Best for Government Contracting
The Unique Entity Identifier (UEI) replaced the DUNS number as the federal standard in 2022 and is now assigned through SAM.gov during entity registration. If you want to bid on federal contracts, apply for federal grants, or receive federal loans, you must be registered in SAM.gov with an active UEI. The registration is free but the process is detailed, requiring business structure, banking, and tax information. SAM registrations must be renewed annually. The UEI is assigned automatically when you complete your SAM profile, making the registration process and number acquisition a single workflow.
Before you buy
Match the number to your actual need
The EIN is universal and should come first. The DUNS, SAM UEI, and LEI are specialized for specific contracting or reporting environments. Getting a number you have no use for wastes time and creates unnecessary compliance obligations.
Verify issuing body legitimacy
EIN and SAM UEI are issued directly by federal agencies at no cost. If a third-party service charges a fee to "obtain" your EIN, they are charging for form filing assistance, not the number itself. Know the difference before paying.
Track renewal requirements
SAM registrations expire annually. LEIs expire annually. State tax IDs in some states require periodic renewal or update filings. A lapsed registration can disqualify you from contracts mid-process.
Keep all numbers in a single secure document
Business registration numbers are targets for identity fraud. Store them in an encrypted business document or password manager, and limit who inside your company has access to the full set.
The wrap-up
For most small businesses, the EIN from the IRS is the single most important corporate number, and it costs nothing to obtain. As your business grows into state-level sales, employees, or government contracts, layer in the state tax ID, DUNS, and SAM UEI in that order. The LEI is a niche requirement for financially regulated entities. Start with what your current business stage demands, document everything, and add r
Quick answers
An EIN (Employer Identification Number) is issued by the IRS and used for federal tax purposes, hiring employees, and opening business bank accounts. A state tax ID is issued by your state's revenue agency and is required for collecting sales tax or filing state payroll taxes. Most businesses that operate across state lines will need both.
Sole proprietors are not required to have an EIN if they have no employees and operate under their own name, but getting one is still strongly recommended. An EIN lets you open a dedicated business bank account, protects your personal Social Security number on vendor forms, and is required if you ever hire help or elect S-corp status later.
Through Dun and Bradstreet's standard process, a DUNS number can take up to 30 business days. However, D&B offers an expedited option that delivers your number within 5 business days for a fee. The DUNS number is free through the standard route and is often required for federal government contracts and grants.
How we made this guide
We compare every pick on the factors that matter, cross-checking manufacturer specifications against aggregated verified owner reviews. We rank independently and never take payment for placement. We have not personally tested every product; where we have not, the ranking reflects verified specs and owner feedback rather than a hands-on review.
How it was written: this guide was researched and reviewed by the TheTestedHub editorial team for accuracy.
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