EIN for Corporations Legal and Tax Uses

Dec. 19, 2025, 5:43 p.m.
An Employer Identification Number (EIN) is a mandatory federal tax ID for corporations operating in the United States. Issued by the IRS, it is used to identify a corporation for tax filing, legal compliance, and financial transactions.
EIN for Corporations

What Is an EIN?

An EIN is a unique nine-digit number assigned by the IRS to business entities. For corporations (C-Corps and S-Corps), an EIN functions like a Social Security Number for the business.

Is an EIN Required for Corporations?

Yes. All corporations in the U.S. are legally required to have an EIN, including:

  • C Corporations

  • S Corporations

  • Professional Corporations (PCs)

  • Nonprofit Corporations

Even a corporation with no employees must obtain an EIN.

Legal Uses of an EIN for Corporations

An EIN is essential for meeting various legal and regulatory requirements, including:

1. Corporate Formation and Registration

  • Required when registering a corporation with state agencies

  • Used in Articles of Incorporation and state filings

2. Opening Business Bank Accounts

  • Banks require an EIN to open corporate checking and savings accounts

  • Necessary for merchant accounts and payment processors

3. Maintaining Corporate Liability Protection

  • Helps separate personal and business finances

  • Supports the corporate veil in legal matters

4. Business Licenses and Permits

  • Federal, state, and local licenses often require an EIN

  • Used in regulatory compliance applications

5. Contracts and Vendor Agreements

  • Frequently requested by clients, vendors, and government agencies

Tax Uses of an EIN for Corporations

Corporations use their EIN for all federal and state tax obligations, including:

1. Filing Federal Corporate Tax Returns

  • C-Corps: Form 1120

  • S-Corps: Form 1120-S

2. Payroll and Employment Taxes

  • Reporting wages and salaries

  • Paying federal withholding, Social Security, and Medicare taxes

  • Filing Forms 941, 940, W-2, and W-3

3. State and Local Tax Filings

  • Corporate income tax

  • Franchise taxes

  • Sales and use tax (where applicable)

4. IRS Communications and Audits

  • Used on all IRS correspondence

  • Required for tax notices, adjustments, and audits

EIN and S Corporation Election

Corporations that elect S-Corp status must already have an EIN before filing Form 2553 with the IRS.

EIN for Multi-State Corporations

Corporations operating in multiple states use the same EIN nationwide, but must register separately with each state for:

  • Foreign qualification

  • State tax accounts

  • Employment registrations

How to Apply for an EIN

Corporations can obtain an EIN for free directly from the IRS:

When a Corporation Needs a New EIN

A corporation must apply for a new EIN if:

  • It incorporates a new legal entity

  • Ownership changes due to a statutory merger

  • It changes from a sole proprietorship or partnership into a corporation

A new EIN is not required for:

  • Name changes

  • Address changes

  • Electing S-Corp status

Common EIN Mistakes Corporations Make

  • Using an owner’s SSN instead of the EIN

  • Applying for multiple EINs unnecessarily

  • Using EINs from dissolved entities

Key Takeaways

 EINs are mandatory for all corporations
 Required for tax filing, payroll, banking, and compliance
 One EIN per corporate entity
 

https://www.irs.gov/businesses/employer-identification-number