How to Change from Sole Proprietor to LLC With the IRS

To change from a sole proprietor to an LLC with the IRS, you handle three things in order: decide whether you need a new Employer Identification Number, choose your federal tax classification (or accept the default), and adjust which return you file going forward. The state paperwork creates the LLC. The IRS side is mostly about telling the agency how you want the new entity taxed and, in some cases, giving it a new number to track.

Here’s the piece most owners miss: if you form a single-member LLC, don’t elect corporate taxation, and don’t have employees or excise tax obligations, you can keep using your existing sole proprietorship EIN and your federal return barely changes.

Do You Need a New EIN?

Answer this first, because it drives everything else. The IRS requires a new EIN in these situations:¹

You’re forming a multi-member LLC. The IRS treats it as a partnership, which is a separate entity from your sole proprietorship.
You have a single-member LLC with employees. Employment tax obligations require an EIN tied to the LLC itself.
You’re electing to be taxed as a C corporation or S corporation. Changing classification creates a new entity for federal purposes.
The LLC will owe excise taxes.

If none of those apply, you can carry your existing EIN over to the single-member LLC. IRS Publication 1635 lays out the full list of triggering scenarios if your situation is unusual.²

Getting the New EIN

The online application at irs.gov/EIN is the fastest route. You complete a short interview and receive your nine-digit number at the end of the session. The tool is open Monday through Friday from 6:00 a.m. to 1:00 a.m. Eastern, Saturday from 6:00 a.m. to 9:00 p.m., and Sunday from 6:00 p.m. to midnight. You’re limited to one EIN per responsible party per day, and the session times out after 15 minutes of inactivity with no way to save progress.³

If your principal place of business is outside the U.S. or you can’t use the online tool, apply by fax or mail using Form SS-4. Either way, have the following ready:

The Social Security Number or ITIN of the responsible party (the person who controls or manages the entity)
The LLC’s legal name exactly as it appears on your state-approved articles of organization
The physical business address
The date the entity was legally formed

Get the LLC name right. A mismatch between the federal application and your state filing produces rejections or account-linking problems later. Print or save the confirmation the moment the online session generates the EIN, because the page cannot be retrieved once you close the browser.

Choosing Your Tax Classification

Forming an LLC does not, on its own, change how the IRS taxes your business income. The default classification depends on how many members the LLC has, and you can override that default with an election form.

The Defaults

A single-member LLC is automatically a “disregarded entity” for federal income tax. The IRS treats the business as though the LLC did not exist, and you continue reporting income and expenses on Schedule C of Form 1040, exactly as before.⁴ The LLC still provides state-law liability protection. Federally, nothing on your return changes.

A multi-member LLC defaults to partnership taxation. The LLC files Form 1065 as an informational return, and each member gets a Schedule K-1 to report their share of income and deductions on their personal return. These default rules come from the entity classification regulations under Internal Revenue Code Section 7701.⁵

Electing Corporate Taxation

To have the LLC taxed as a C corporation, file Form 8832, Entity Classification Election.⁶ Each member who owns an interest at the time of filing must sign, along with anyone who was an owner during a retroactive effective period but is no longer.⁷

For S-corp treatment, file Form 2553, Election by a Small Business Corporation.⁸ You don’t need to file Form 8832 first. An LLC that timely files Form 2553 and meets all S-corp requirements is automatically deemed to have elected corporate classification. All shareholders sign the consent statement on the form.

One long-term consequence to know before you file Form 8832: once you change classification, you generally can’t change again for 60 months. The IRS may grant an exception through a private letter ruling if more than 50% of ownership interests have changed hands since the prior election. The restriction doesn’t apply if the original election was made by a newly formed entity and took effect on its formation date.

Election Deadlines

Missing the deadline is one of the most common mistakes.

For Form 2553, file no later than two months and 15 days after the beginning of the tax year you want the election to cover. For a newly formed LLC, the clock starts when the entity has members, acquires assets, or begins doing business, whichever happens first. Miss the window and the election takes effect the following tax year unless you qualify for late-election relief.⁹

For Form 8832, the effective date you choose cannot be more than 75 days before you file the form and cannot be more than 12 months after. If you enter a date outside those bounds, the IRS adjusts it to the nearest allowed date.⁷

Late elections on either form require a reasonable-cause explanation. The IRS grants relief more often than owners expect, but the process is slower and the outcome isn’t guaranteed.

You should hear back on Form 2553 within about 60 days, or 90 days more if you requested a specific tax year on box Q1 in Part II. The IRS confirms an accepted S-corp election with a CP261 notice.¹⁰ Keep that notice permanently. You’ll need it for audits, loans, and other financial applications. If you filed by fax, save the confirmation sheet as your proof of timely filing.

How Your Tax Return Changes

What you actually file depends on the classification you ended up with.

Single-member LLC treated as a disregarded entity. Business income and expenses stay on Schedule C of Form 1040.⁴ Rental real estate goes on Schedule E; farming goes on Schedule F.¹¹ No separate business return is required.

Multi-member LLC treated as a partnership. The LLC files Form 1065 by March 15 (or the 15th day of the third month after the tax year ends). Income passes through to members on Schedule K-1.

LLC taxed as an S corporation. The LLC files Form 1120-S annually and issues Schedule K-1s. Any owner who works in the business must be paid a reasonable salary as a W-2 employee before taking distributions. The IRS requires that payments to a corporate officer be treated as wages to the extent they represent reasonable compensation for services.¹²

If the LLC has employees, update your payroll records so the new entity name and EIN appear on Form 941, the quarterly employment tax return, and on Form 940 for federal unemployment taxes.¹³ If you don’t, deposits get credited to the wrong account and you’ll spend months clearing up penalty notices.

Closing the Old Sole Proprietorship EIN

If you obtained a new EIN for the LLC, close the old sole proprietorship EIN account so the IRS doesn’t keep expecting returns under it. Send a letter with the business’s legal name, the old EIN, the business address, and the reason for closing. Include a copy of the original EIN assignment notice if you have it. Mail everything to:

Internal Revenue Service
Cincinnati, OH 45999

The IRS won’t close the account until all required returns have been filed and all taxes paid under that EIN.¹⁴ File a final Schedule C covering January 1 through the date you stopped operating as a sole proprietorship. The LLC picks up from there. Keep clear records of the transition date, because overlapping periods or gaps between the two returns are the kind of thing that produces follow-up letters.

Self-Employment Tax and the S-Corp Question

Self-employment tax is where classification has the biggest dollar impact, and it’s the main reason owners consider the S-corp election.

As a sole proprietor or single-member LLC (disregarded entity), you owe self-employment tax of 15.3% on 92.35% of your net business income. That covers both the employer and employee shares of Social Security (12.4%) and Medicare (2.9%). In 2026, the Social Security portion applies to the first $184,500 of combined wages and self-employment income; Medicare has no cap.¹⁵

With an S-corp election, only your W-2 salary is subject to payroll taxes. Distributions above that salary aren’t hit with the 15.3%. The catch is what “reasonable” means. If you set your salary too low to dodge payroll taxes, the IRS can reclassify distributions as wages.¹² Reasonable compensation is measured against what similar businesses pay for comparable work. The savings only make sense once net income is high enough that the payroll tax reduction outweighs the added cost of running payroll, filing Form 1120-S, and issuing W-2s.

1
Internal Revenue Service. When to Get a New EIN
2
Internal Revenue Service. Understanding Your EIN
3
Internal Revenue Service. Get an Employer Identification Number
4
Internal Revenue Service. Single Member Limited Liability Companies
5
Office of the Law Revision Counsel. 26 USC 7701 – Definitions
6
Internal Revenue Service. About Form 8832, Entity Classification Election
7
Internal Revenue Service. Form 8832 Entity Classification Election
8
Internal Revenue Service. About Form 2553, Election by a Small Business Corporation
9
Internal Revenue Service. Instructions for Form 2553
10
Internal Revenue Service. Understanding Your CP261 Notice
11
Internal Revenue Service. About Schedule C (Form 1040), Profit or Loss from Business (Sole Proprietorship)
12
Internal Revenue Service. Publication 15 (2026), (Circular E), Employers Tax Guide
13
Internal Revenue Service. About Form 941, Employers Quarterly Federal Tax Return
14
Internal Revenue Service. Closing a Business
15
Social Security Administration. What Is the Current Maximum Amount of Taxable Earnings for Social Security