Business structures and their tax basics: sole prop, LLC, S-corp
When you start or restructure a business, the legal form you choose determines how the IRS and state agencies treat your income, deductions, and self-employment obligations. This guide explains the key differences between common structures so you can have a more informed conversation with a tax professional before making a decision.
What is pass-through taxation and why does it matter?
Pass-through taxation means the business itself does not pay federal income tax. Instead, profits and losses flow directly to the owners' personal returns, where they are taxed at individual rates. Most small-business structures use this model.
The alternative is corporate-level taxation, where the business pays tax on its earnings and shareholders pay tax again on dividends. The IRS calls this double taxation. Because of it, many small-business owners choose structures that avoid it -- though there are trade-offs worth discussing with a tax professional.
Pass-through structures recognized by the IRS include:
- Sole proprietorships
- Single-member LLCs (disregarded entities)
- Multi-member LLCs (taxed as partnerships by default)
- S corporations
- Partnerships
How do common structures differ for tax purposes?
Sole proprietorship
A sole proprietorship is the default structure when an individual earns business income without forming a separate entity. Income and expenses are reported on Schedule C, attached to Form 1040. The net profit is subject to both income tax and self-employment tax. No separate business return is required.
Single-member LLC
By default, the IRS treats a single-member LLC as a disregarded entity -- the tax treatment is nearly identical to a sole proprietorship. The owner still files Schedule C and pays self-employment tax on net earnings. The LLC classification is a legal distinction at the state level, not a federal tax classification on its own.
Multi-member LLC
A multi-member LLC is taxed as a partnership by default. The LLC files Form 1065 (an informational return) and issues each member a Schedule K-1 showing their share of income, deductions, and credits. Members generally pay self-employment tax on their distributive share of business income, though the exact treatment depends on their role and the activity involved.
S corporation
An S corporation is a corporation that has elected to be taxed as a pass-through entity under Subchapter S of the Internal Revenue Code. It files Form 1120-S and issues K-1s to shareholders. A key distinction: shareholder-employees must pay themselves a reasonable salary, which is subject to payroll taxes. Distributions above that salary are generally not subject to self-employment tax -- a difference that has both potential advantages and compliance requirements. The IRS scrutinizes S-corp compensation closely; the salary must be defensible.
To elect S-corp status, a corporation must meet eligibility requirements (including a limit on the number and type of shareholders) and file Form 2553 within the required timeframe.
C corporation
A C corporation is taxed at the entity level under its own rate. It is generally less common among small businesses because of the double-taxation dynamic, but there are situations where a qualified tax professional might identify it as worth considering for specific circumstances.
What does entity choice actually affect on your taxes?
| Structural factor | Sole prop / SMLLC | Partnership / MMLLC | S-corp |
|---|---|---|---|
| Business-level federal return | None (Sch C) | Form 1065 | Form 1120-S |
| Self-employment tax on all net profit | Yes | Generally yes | Only on salary portion |
| Payroll requirements | No | No (unless employees) | Yes -- owner must be on payroll |
| State-level fees and filings | Varies | Varies | Varies -- often higher |
State tax treatment can differ from federal. Some states impose franchise taxes, minimum taxes, or additional filings on LLCs and corporations regardless of profitability. Check with your state's department of revenue or a tax professional familiar with your state.
Why entity choice warrants professional input
The decision is not purely a tax question. Liability protection, ownership structure, the number of owners, the ability to bring in investors, and the administrative burden of maintaining the entity all factor in. A change in structure can also trigger tax events -- converting from a sole proprietorship to an S-corp, for example, involves steps that should be handled carefully.
Tax professionals who work with small-business owners can model the projected tax impact of different structures based on your specific income level and circumstances. They can also flag state-level requirements that may not be obvious from federal guidance alone.
Where to get help
If you are weighing entity structure options or want to understand how your current structure affects your tax obligations, find a tax professional who works with self-employed clients and small businesses.
Sources
- IRS: Business Structures -- overview of each entity type and associated federal returns
- IRS: S Corporations -- eligibility, election requirements, and Form 1120-S
- IRS: Self-Employment Tax -- rates and applicability by structure
- IRS: Schedule C (Form 1040) -- sole proprietorship and disregarded-entity reporting
- IRS: Partnerships -- Form 1065 and K-1 requirements
- Your state's Department of Revenue or Department of Taxation -- for state-specific LLC fees, franchise taxes, and registration requirements