Side Business

Sole Proprietor or LLC? What Changes for a Side Business

By Camille Laurent / November 12, 2026

A smiling young woman writes on a clipboard of papers at a desk with an open laptop, surrounded by stacked cardboard boxes and a rack of clothes in a small home-based business.

Why do so many people say a side business “needs an LLC” when the IRS treats a one-person LLC almost like no entity at all? Because the two structures differ sharply on one thing and barely on another. A sole proprietorship is what you are by default once you earn money under your own name. A single-member LLC is a separate legal shell created under state law. The SBA says that shell protects your personal assets in most instances, while the IRS says a one-owner LLC is generally ignored for federal income tax: you still use Schedule C and still pay self-employment tax. So an LLC mostly changes liability and paperwork, not your federal income tax. Here is what changes, what does not, and what to ask a professional.

Key takeaways

A sole proprietorship has no legal identity apart from you. The SBA says you can be held personally liable for the business’s debts and obligations.
A single-member LLC is generally a “disregarded entity” for federal income tax unless the owner elects corporate treatment. You report it on your own return, typically on Schedule C.
Self-employment tax hits the owner the same way in both cases: 15.3 percent on net earnings, within limits.
An LLC costs money and paperwork that vary by state. The SBA says registering usually totals under $300, but fees vary.
An LLC does not remove every risk, and it works as intended only if business and personal money stay apart.

Why the two structures exist

A sole proprietorship is the absence of a decision. The SBA says you are one automatically if you do business and have not registered as anything else. The IRS describes it as an unincorporated business with no legal identity apart from its owner, whose debts are the owner’s.

An LLC is created by state statute, which explains the confusion. The state decides what an LLC means for liability, and the federal government separately decides how to tax it. Two authorities, two answers.

Liability: the real difference

This justifies the fuss. For a sole proprietor, the SBA says business and personal assets and liabilities are not separate. For an LLC, it says your vehicle, house and savings should not be at risk if the LLC faces bankruptcy or lawsuits, but it hedges with “in most instances” and notes that rules vary by state. Which instances fall outside the shield is a question for an attorney in your state.

What an LLC does not protect

The pages we read give no full list of exceptions, so treat these as questions to ask, not legal conclusions:

Mixed money. The SBA says a business bank account offers limited personal liability protection by keeping business and personal funds apart.
Skipped registration. The SBA warns that an unregistered business could miss out on personal liability protection.
Contracts you sign personally. Say a landlord or lender wants your own signature. Ask an attorney how that interacts with the LLC.
Your own actions. Whether the shell covers harm you personally cause depends on state law and the facts.
Self-employment tax. The LLC does not remove it, as covered next.
Insurance gaps. The SBA lists business insurance as its own launch step. An entity is not a substitute.

Taxes: mostly the same

The IRS says a one-member LLC is disregarded as separate from its owner unless it files Form 8832 and elects corporate treatment. Absent that, the activity generally goes on Schedule C (Form 1040), the form a sole proprietor uses for business income and expenses.

Self-employment tax

The IRS says the owner of a single-member LLC that runs a trade or business owes self-employment tax in the same manner as a sole proprietor. Topic 407 says net earnings from Schedule C of $400 or more require Schedule SE. The rate is 15.3 percent: 12.4 percent Social Security plus 2.9 percent Medicare. For 2026, the first $184,500 of combined wages, tips and net earnings is subject to the Social Security part. An extra 0.9 percent Medicare tax applies above thresholds by filing status, such as $200,000 for single filers and $250,000 for joint filers. You can deduct the employer-equivalent half when figuring adjusted gross income. The IRS updates these limits, so check its page.

Where the LLC does differ

The IRS says a single-member LLC is still a separate entity for employment tax and certain excise taxes, so if you hire an employee, the LLC uses its own name and EIN for employment tax. A disregarded LLC without employees generally does not need an EIN, though it can get one if a bank or state requires it. On a Form W-9, the IRS says the owner’s SSN or EIN goes in, not the LLC’s. Corporate or S corporation treatment is a separate decision; the SBA says it is harder to set up and calls for a counselor or attorney.

Side by side

Question	Sole proprietorship	Single-member LLC
Legal identity	None apart from the owner (IRS)	Separate entity under state law (IRS, SBA)
Personal liability for business debts	Yes (SBA)	Generally not, “in most instances” (SBA)
Federal income tax form	Schedule C (IRS)	Usually Schedule C if no corporate election (IRS)
Self-employment tax	Owner pays (IRS)	Owner pays, same manner (IRS)
State filing	None if you use your own legal name (SBA)	Articles of organization, registered agent (SBA)
Operating agreement	Not applicable	Widely recommended (SBA)
Ongoing state costs	Depends on state and local licence or DBA rules	Varies by state (SBA)

State fees, annual reports and one example

Here the answer is “it depends on your state.” The SBA says documents and fees vary by state and structure, and that an LLC active in more than one state might need foreign qualification and typically pays taxes and annual report fees in each.

For a sense of the spread, take California. Its Franchise Tax Board says every LLC doing business or organized there must pay an annual tax of $800, due even if you are not conducting business until you cancel the LLC, and that an LLC making more than $250,000 owes an additional fee. That is one state’s rule as of the page we read. Other states differ, so check your own Secretary of State or business agency. Price the ongoing cost before you pay the formation fee.

Licences, DBA names and the bank account

Licences and permits

The SBA says requirements and fees vary by activity, location and government rules, and most small businesses need some mix of federal, state and local permits. An LLC does not replace them.

DBA names

A “doing business as” name (trade, fictitious or assumed name) may need registering with the state, county or city. The SBA says a DBA gives no legal protection by itself, but most states require registration if you use one. A sole proprietor can have a trade name too.

The separate bank account

The SBA says to open a business account as soon as you start accepting or spending money as your business, once you have an EIN. A sole proprietor can do this as well, and it tidies the Schedule C. For an LLC it is the practical evidence that the business is its own thing.

A decision checklist

List what could go wrong: an injured customer, a damaged item, a contract dispute, a lease. The SBA calls sole proprietorships a fit for low-risk businesses.
List personal assets you would hate to expose. The SBA says LLCs suit owners with significant assets to protect.
Look up your state’s LLC formation fee, annual report or tax, and registered agent rules.
Check local licence and DBA rules, whichever structure you pick.
Price business insurance separately.
Get an EIN if you will hire, or if the bank or state asks.
Open a separate bank account and run all business money through it.
If you form an LLC, ask about an operating agreement.
Ask a CPA how the Schedule C and state taxes will look, and an attorney which liability gaps remain.
Revisit as the business grows. The SBA says converting later may bring restrictions and tax consequences.

Frequently asked questions

Does an LLC lower my federal income tax?

Not by itself. The IRS says a one-member LLC is generally disregarded for income tax, so income goes on your return, typically Schedule C, with self-employment tax as for a sole proprietor.

Do I have to form an LLC to run a side business?

No. The SBA says you are a sole proprietor automatically if you do business and register as nothing else. Whether to form one is a risk and cost question.

Can I form an LLC while keeping my day job?

The pages we read do not address employer rules. Check your employment agreement and ask an attorney.

Will an LLC protect me from every lawsuit?

The sources do not promise that. The SBA says protection applies in most instances and that state rules vary. An attorney can explain the exceptions for your state.

Before you decide

A sole proprietorship is cheap and simple but leaves personal assets exposed. A single-member LLC adds protection for a state-by-state price while leaving your federal income tax largely unchanged. If the side business is small and low-risk, staying a sole proprietor while you test the idea is a recognised path. If real customers or a lease are involved, an LLC may earn its fee. Before filing, ask a CPA about tax and an attorney licensed in your state about liability.