To convert a sole proprietorship to an S corp, you form a new legal entity (either a corporation or an LLC) with your state, get a new Employer Identification Number, file IRS Form 2553 to elect S corporation tax treatment, transfer your business assets and liabilities into the entity, and put yourself on payroll. The point of doing all this is to cut self-employment tax: a sole proprietor pays 15.3% Social Security and Medicare tax on the entire net profit, while an S corp owner pays those employment taxes only on the W-2 salary they draw and takes remaining profits as distributions that avoid the 15.3% hit.
Is the Switch Worth It for Your Business
The tax savings look attractive on paper, but running an S corp costs money that a sole proprietorship doesn’t. You have to run payroll, file a separate corporate tax return, and pay state franchise or annual report fees where they apply. Those costs typically add up to $1,500 to $3,000 per year at a minimum.
The rough threshold: S corp status starts making financial sense when net profit consistently exceeds around $60,000 to $80,000 a year. Below that, compliance costs usually swallow the tax savings. Between $40,000 and $60,000, the numbers are close enough that you should model them with a tax professional before committing. Above $80,000, the savings almost always come out ahead.
One deduction worth checking before you decide is the Section 199A qualified business income deduction, which allowed eligible business owners to deduct up to 20% of qualified business income. It was scheduled to expire for tax years beginning after December 31, 2025.1Internal Revenue Service. Qualified Business Income Deduction Congress may extend it, so confirm the current status for your tax year before you factor it in.
Corporation or LLC as the Underlying Entity
“S corp” is a tax status, not an entity type. You can form a state-law corporation and elect S treatment, or you can form an LLC and elect S treatment. The IRS lets any entity eligible to be treated as a corporation file the S election.2Internal Revenue Service. About Form 2553, Election by a Small Business Corporation
For most sole proprietors, the LLC route is simpler. A corporation requires a board of directors, officer elections, bylaws, annual meetings, and recorded minutes. Slipping on those formalities can weaken the liability shield the corporate form is supposed to provide. An LLC operates under an operating agreement with far fewer maintenance obligations in most states. Both structures give you the same personal liability protection and the same S corp tax result once the election is on file.
A single-member LLC is disregarded for federal tax purposes by default. Filing Form 2553 causes the IRS to treat that LLC as a corporation that has elected S status; you do not need to separately file Form 8832 first.3Internal Revenue Service. About Form 8832, Entity Classification Election
Forming the Entity With Your State
The new entity is created by filing formation documents with the Secretary of State (or equivalent agency) in the state where the business operates. For a corporation, that’s Articles of Incorporation. For an LLC, it’s Articles of Organization or a Certificate of Formation, depending on state terminology.
Search the state’s business name database first to confirm your desired name is available. You’ll also designate a registered agent in the state, meaning a person or service authorized to accept legal documents for the entity. The filing itself lists the entity name, the registered agent’s name and address, and, for corporations, the number of authorized shares. Filing fees generally run from about $50 to $300, though a few states charge more. Once the state approves the filing, the entity legally exists as separate from you.
Getting a New EIN
The new entity needs its own EIN. You cannot reuse the sole proprietorship’s EIN or your Social Security number. The IRS online application issues the number immediately at no cost.4Internal Revenue Service. Get an Employer Identification Number If you’re applying from outside the U.S. or want a paper trail, submit Form SS-4 by fax or mail.5Internal Revenue Service. Instructions for Form SS-4 Every bank account, tax return, and payroll filing for the business now uses this number.
Filing Form 2553 to Elect S Status
A newly formed corporation defaults to C corporation status, meaning the entity pays income tax and the owners get taxed again on distributions. Form 2553 replaces that with pass-through treatment.6Internal Revenue Service. Instructions for Form 2553
Eligibility
To qualify, the entity must be domestic and meet these limits:
- No more than 100 shareholders. Family members and their estates count as a single shareholder.
- Shareholders can only be U.S. citizens or residents, certain trusts, or estates. Partnerships, other corporations, and nonresident aliens are not eligible.
- Only one class of stock, though voting differences among common shares are allowed.
- Certain financial institutions, insurance companies, and domestic international sales corporations cannot elect S status.
Deadline
To make the election effective for the current tax year, file Form 2553 no later than two months and 15 days after the tax year begins, which is March 15 for calendar-year businesses. You can also file it any time during the preceding tax year.8Office of the Law Revision Counsel. 26 USC 1362 – Election, Revocation, Termination File later than that and the election applies to the following tax year instead. Every shareholder must sign; as a sole owner, that’s just you.
If You Miss the Deadline
Revenue Procedure 2013-30 lets you file late if you do so within three years and 75 days of the intended effective date. You must show reasonable cause for the delay and demonstrate that the business and all shareholders have reported income consistently with S corp status for the period in question. Write “FILED PURSUANT TO REV. PROC. 2013-30” in the top margin of Form 2553.6Internal Revenue Service. Instructions for Form 2553
Moving Assets and Liabilities Into the Entity
Once the entity has its EIN, transfer the sole proprietorship’s assets into it. The standard approach is to contribute equipment, inventory, receivables, intellectual property, and customer lists in exchange for stock in the corporation or membership interest in the LLC.
Document tangible property transfers with a Bill of Sale and intangibles with an Assignment Agreement. Leases for space or equipment need to be formally assigned or re-executed in the new entity’s name.
The tax side is favorable. Under Section 351 of the Internal Revenue Code, no gain or loss is recognized when you transfer property to a corporation solely in exchange for stock, provided you control the corporation immediately after the exchange.9Office of the Law Revision Counsel. 26 US Code 351 – Transfer to Corporation Controlled by Transferor As the sole owner, the control test is automatic. The corporation takes your existing basis in the assets, with no immediate tax bill.
Existing liabilities, such as business loans or lines of credit, need formal transfer too. Lenders typically require an assumption agreement or loan modification, and this is where many conversions stall because the lender may want to re-underwrite based on the new entity’s financials.
Putting Yourself on Payroll
The S corp’s tax advantage lives in payroll, and the IRS watches this piece closely. As a sole proprietor, your entire net profit is subject to self-employment tax at 15.3%, covering both the employer and employee shares of Social Security (6.2% each) and Medicare (1.45% each).10Internal Revenue Service. Topic No. 751, Social Security and Medicare Withholding Rates As an S corp owner-employee, only your W-2 salary is subject to those taxes. Distributions of remaining profit are not.
The catch is reasonable compensation. Any shareholder who performs services for the S corp must receive a reasonable salary before taking distributions. Paying yourself $20,000 for work that would command $80,000 on the open market and pulling the rest as distributions invites the IRS to reclassify those distributions as wages, with back taxes, interest, and penalties attached.
What Reasonable Compensation Means
The IRS and courts weigh several factors:11Internal Revenue Service. Wage Compensation for S Corporation Officers
- Your training and experience, and what they would command in the market.
- The actual duties you perform and hours involved.
- What comparable businesses pay for similar roles.
- The company’s history of dividends and distributions relative to wages.
- Whether the salary was set through a deliberate, documented process.
The defensible approach is to pull salary data for your role and industry, set compensation at a supportable level, and record the reasoning in a corporate resolution. Lowballing the salary is the single most common audit trigger for S corp owner-employees.
Payroll Setup
Register the entity as an employer with the state workforce agency for unemployment insurance. Set up payroll software or a payroll service using the new corporate EIN. The corporation withholds federal income tax, the employee share of FICA, and any state taxes from each paycheck, then remits those amounts along with the employer share of FICA to the IRS.
Payroll taxes get reported quarterly on Form 941.12Internal Revenue Service. Topic No. 758, Form 941 and Form 944 At year end, issue yourself a W-2. The corporation also owes federal unemployment tax, filed annually on Form 940.13Internal Revenue Service. S Corporations
Cleaning Up the Operational Side
Open new bank accounts (checking and savings) in the entity’s legal name with the new EIN. Every business transaction from this point on must run through those accounts. Commingling personal and business funds is the fastest way to lose the liability protection the new structure exists to provide.
Update business licenses and permits with state, county, and municipal authorities. Notify vendors, suppliers, and customers so contracts, invoices, and payments reflect the new entity. If you formed a corporation rather than an LLC, hold an organizational meeting of directors and shareholders, adopt bylaws, elect officers, record everything in a minute book, and issue stock certificates in exchange for the contributed assets. Courts look at whether owners actually maintained these records when deciding whether creditors can reach personal assets.
What You’ll File Every Year Now
The federal income tax return is Form 1120-S, due by the 15th day of the third month after the tax year ends. For calendar-year S corps, the 2025 return is due March 16, 2026, because March 15 falls on a Sunday.14Internal Revenue Service. Instructions for Form 1120-S (2025) Form 7004 buys a six-month extension to file, but any tax owed is still due on the original date.
The S corp itself generally doesn’t pay federal income tax. It passes income, losses, deductions, and credits through to you on a Schedule K-1, which you report on your personal Form 1040 (Schedule E).15Internal Revenue Service. Shareholder’s Instructions for Schedule K-1 (Form 1120-S) You stop filing Schedule C for the business once the conversion is complete.16Internal Revenue Service. About Schedule C (Form 1040), Profit or Loss from Business (Sole Proprietorship) If you convert mid-year, file a final short-year Schedule C for the sole proprietorship period and report S corp income on Schedule E for the rest of the year.
Beyond the income tax return, you’ll file Form 941 quarterly, Form 940 annually, and W-2s and W-3s at year end. Most states also require an annual report or franchise tax filing for the entity, with fees that vary widely. Some states do not automatically recognize the federal S election and require a separate state-level filing, so check with your state’s tax authority to avoid an unexpected state tax bill.
Undoing the Election Later
If S status stops making sense, you can revoke it. Revocation requires the consent of shareholders holding more than half of the shares. File a revocation statement with the IRS; if it’s submitted by March 15 of the tax year, the revocation takes effect January 1 of that year. Filed after March 15, it takes effect the following January 1 unless you specify a later date.8Office of the Law Revision Counsel. 26 USC 1362 – Election, Revocation, Termination
One warning worth taking seriously: once the S election is revoked or terminated, the corporation (and any successor) generally cannot re-elect S status for five tax years without IRS consent. That lockout makes revocation worth thinking through carefully rather than acting on after one slow year.