An Employer Identification Number (EIN) is a unique federal tax ID assigned by the IRS to identify a business entity for tax and reporting purposes. When a business is issued an EIN, the IRS provides an official confirmation document known as an EIN letter, often referred to as a CP 575. This letter serves as proof of your company’s legal identity and is required in many essential business processes. Banks use it to open business accounts, lenders request it during funding applications, payroll providers need it to set up employee wages, and vendors or platforms often require it to verify your business before onboarding. Because it functions as formal IRS documentation, the EIN letter is one of the most important compliance documents a business should keep on file.
What is an EIN Letter?
An EIN letter is the official confirmation document the IRS issues after assigning a business its Employer Identification Number. Commonly called a CP 575 letter, it verifies your company’s federal tax ID and includes key details such as your legal business name, address, and tax classification. This letter serves as formal proof that your EIN is active and registered with the IRS. Whether a business is newly formed or undergoing changes, the EIN letter is a foundational document used for tax reporting, banking, hiring, and most compliance-related activities.
What an EIN Letter Includes
The Assigned EIN
The letter lists your official Employer Identification Number, the unique tax ID the IRS uses to identify your business.
Legal Business Name and Address
It confirms the exact legal name and mailing address associated with your EIN—details banks and lenders must match precisely.
Filing Requirements and Tax Classification
The letter outlines your federal tax classification (such as LLC, corporation, partnership, or sole proprietor) and explains your reporting responsibilities.
IRS Reference Information
It includes IRS contact information, the date your EIN was issued, and important notices or instructions related to your tax obligations.
Why Do Businesses Need an EIN Letter?
Businesses rely on their EIN letter as official proof of their federal tax ID, making it an essential document across many operational and financial processes. Banks require the EIN letter to open business accounts, while lenders use it during underwriting to verify a company’s legal identity before approving funding. It’s also necessary for setting up payroll, hiring employees, and ensuring wages and taxes are correctly reported. Beyond internal operations, vendors, suppliers, and online platforms often request the EIN letter to validate a business before onboarding or extending credit terms. Because it serves as formal IRS verification, keeping the EIN letter accessible is critical for smooth banking, compliance, and financial management.
How to Get an EIN Letter?
Businesses receive their EIN letter automatically after applying for an Employer Identification Number through the IRS. The fastest method is applying online, where the EIN is issued immediately and the confirmation letter can be downloaded on the spot. Companies can also apply by fax or mail, though these options take longer to process. Once the EIN is approved, the IRS generates the official CP 575 confirmation letter, which serves as proof of your business’s federal tax ID. Regardless of the application method, the EIN letter becomes a critical document for banking, tax filing, payroll setup, and other business verifications.
Lost Your EIN Letter? How to Get a Replacement?
If your EIN letter is misplaced, the IRS can issue a replacement known as an EIN Verification Letter, also called a Form 147C. To request it, you must call the IRS Business & Specialty Tax Line and verify your identity using details such as your legal business name, address, and EIN. Once verified, the IRS will mail or fax the 147C letter, depending on your preference. While processing times vary, faxed copies typically arrive the same day, while mailed versions may take up to two weeks. Keeping a digital and printed copy of the replacement ensures you always have access to official proof of your business’s federal tax ID.
EIN Letter vs. EIN Number – What’s the Difference?
Many business owners confuse the EIN itself with the EIN letter, but they serve two different purposes. The EIN number is simply your business’s federal tax ID, similar to a Social Security number for individuals and is used on tax returns, payroll forms, and financial documents. The EIN letter, on the other hand, is the official IRS document that confirms the EIN was issued and verifies the legal business name and address attached to it. While the number alone is often enough for routine filings, banks, lenders, payroll providers, and many vendors require the EIN letter as formal proof of the business’s identity. Together, the number and the letter ensure your company is properly recognized and authenticated across financial and compliance-related processes.
Common Mistakes and Misconceptions
Many businesses make avoidable mistakes when dealing with their EIN letter. One common misconception is assuming that the email confirmation received during the application process is the same as the official CP 575 letter, it’s not. Another frequent error is confusing a federal EIN with a state tax ID, which is issued separately and used for different compliance purposes. Some business owners also believe they need to renew their EIN, but EINs never expire and remain tied to the business permanently unless major structural changes occur. Additionally, failing to update the IRS when a business changes its legal name or address can lead to verification issues with banks, lenders, and payroll providers. Staying aware of these details helps ensure smooth financial operations and avoids unnecessary delays.
Key Takeaways
An EIN letter is one of the most important documents a business can have, serving as official proof of its federal tax identification and playing a critical role in banking, payroll, compliance, and funding. While the EIN number itself is essential for tax reporting, the EIN letter verifies your company’s legal identity in a way many financial institutions and vendors require. Keeping this document accessible, both digitally and in print, ensures smooth operations and prevents delays when opening accounts, applying for financing, or onboarding with new partners. Whether you’re forming a new business or organizing existing records, maintaining your EIN letter is a simple step that protects your company and supports long-term growth.
