The CP 575B is the one-time letter the IRS mails to confirm that your business has been assigned an Employer Identification Number. It lists the nine-digit EIN, the legal name on file, the mailing address, and the date the number took effect, and it’s what banks and other agencies ask for when they need to verify that your business’s tax identity is real. The IRS issues this notice only once, so what you do with it (and what you do if you lose it) matters.
What’s on the Notice
The letter is short and lists four things you’ll want to check the day it arrives:
- The EIN itself, formatted as XX-XXXXXXX. This is the number you’ll put on every federal return, payroll filing, and bank application.
- The legal name of the entity, exactly as the IRS recorded it from your application. This has to match your state formation documents and your bank paperwork. Even a small mismatch, like an ampersand where the state filing spells out “and,” can stall an account opening.
- The mailing address you provided on the application. That becomes the IRS’s default address for future correspondence until you change it.
- The effective date the EIN was assigned. From this date forward, the business is active in the federal tax system.
If any of these details are wrong, fix them before you file returns or open accounts. Mismatches between the CP 575B and your state registration or bank records are one of the most common reasons new businesses hit early delays.
When It Arrives
Timing depends on how you applied. The online application through the IRS issues an EIN immediately on screen, and you can print that confirmation right away. The formal CP 575B letter follows separately by mail, typically within four to six weeks.1Internal Revenue Service. Get an Employer Identification Number
Fax applications using Form SS-4 generally produce an EIN within four business days, with a faxed confirmation back. Mailed applications often take four to six weeks just for initial processing. Whichever route you used, the CP 575B is the paper confirmation that eventually shows up at the address on your application.
The printed online confirmation works in the short term, but some banks and state agencies specifically want the CP 575B (or its replacement, the 147C letter). If you need to open a business account quickly, call ahead and ask which one the institution will accept.
Where You’ll Use It
Banks ask for the CP 575B because it’s the cleanest way to verify that your EIN, legal name, and entity type match what the IRS has on file. Without it, most institutions won’t open a commercial account in the business’s name.
You’ll also reference the EIN on every federal return the business files. Corporations enter it on Form 1120.2Internal Revenue Service. Instructions for Form 1120 (2025) – Section: Item B. Employer Identification Number (EIN) Partnerships enter it on Form 1065.3Internal Revenue Service. 2025 Instructions for Form 1065 – Section: Item D. Employer Identification Number (EIN) If you hire employees, the EIN goes in the header of Form 941, the quarterly return for withheld income tax and Social Security and Medicare taxes,4Internal Revenue Service. Form 941, Employer’s QUARTERLY Federal Tax Return and on Form 940 for federal unemployment tax.
Because the IRS issues the notice only once, store the original the way you’d store a deed or an original contract. A fireproof safe or a corporate records binder is the right home for the physical copy. Keep a scanned backup somewhere encrypted and separate. Your EIN functions much like a Social Security number for the business, and anyone who has it can potentially file fraudulent returns or open accounts in the entity’s name.
If You Lose It: Requesting a 147C Letter
The IRS will not reissue the original CP 575B. If yours is lost, damaged, or a bank refuses a faded copy, what you can get is a 147C letter, which carries the same verification weight.
Call the IRS Business and Specialty Tax line at 800-829-4933 to request one.5Internal Revenue Service. Telephone Assistance Contacts for Business Customers – Section: Business and Specialty Tax Line and EIN Assignment (800-829-4933) The agent verifies your identity and the business details, then either faxes the 147C while you’re still on the phone or mails it (again, four to six weeks). If a bank is pressing you, ask for the fax.
Only the responsible party on the EIN application, or someone the IRS has authorized to act for the entity, can make this call. If you want your accountant or attorney to handle it, they need a Form 2848 Power of Attorney on file first, listing “EIN Application” as the matter and “Form SS-4” as the tax form number.6Internal Revenue Service. Instructions for Form 2848 Power of Attorney and Declaration of Representative
Fixing Errors on the Notice
Check the notice carefully when it arrives. Correcting an error now takes a few minutes. Correcting it during tax season, after a mismatch triggers a rejection, takes much longer and can bring penalties.
Name Corrections
How you fix a name error depends on the entity. Sole proprietors write to the IRS at the address where they’d file their return and explain the correct name. Corporations can check the name-change box on Form 1120 (Line E, Box 3) with their next return, or write to the IRS if they’ve already filed. Partnerships do the same on Form 1065 (Line G, Box 3).7Internal Revenue Service. Business Name Change In some situations a name change requires an entirely new EIN; IRS Publication 1635 spells out when.
Address Corrections
To update the mailing address, file Form 8822-B, Change of Address or Responsible Party — Business. Processing generally takes four to six weeks.8IRS. Form 8822-B Change of Address or Responsible Party – Business Until the change goes through, the IRS keeps sending correspondence to whatever address is on the CP 575B, so file promptly after any move.
Keep the Responsible Party Current
The responsible party is the individual who ultimately owns or controls the entity, with the practical ability to direct its funds and assets.9Internal Revenue Service. Instructions for Form SS-4 (12/2025) For a corporation that’s typically the principal officer, for a partnership a general partner, for a trust the grantor or trustee.
When that person changes (a buyout, a leadership transition, a new trustee) you’re required to report the change to the IRS within 60 days using Form 8822-B.8IRS. Form 8822-B Change of Address or Responsible Party – Business This is more than housekeeping. The responsible party on record is who the IRS contacts about the account, and who can call in and request a 147C letter or make changes to the entity’s information. If that person doesn’t match the person actually running the business, you can find yourself locked out of your own IRS account when you need access most.
If you file Form 8822-B and don’t get a confirmation back within 60 days, mail the form again with “Second Request” written on it.10Internal Revenue Service. Responsible Parties and Nominees