Sole Proprietor Vs LLC Vs S Corp Tax Differences Explained

A sole proprietorship pays income tax plus a 15.3% self-employment tax on all profit, whereas an S Corp splits profit into a reasonable salary (subject to that 15.3% tax) and distributions (not subject to it), and an LLC is not a tax classification but a legal entity that can choose to be taxed as either of the above.

The sole proprietor vs LLC self-employment tax trap people miss

The 15.3% self-employment tax is the silent killer for sole proprietors. It applies to every dollar of net profit, not just what you withdraw. On a Schedule C profit that the IRS sees as $100,000, you pay $14,130 in self-employment tax before you touch income tax. That is $14,130 that goes to Social Security and Medicare, and there is no employer match because you are both the boss and the employee. The trap is that this tax has no ceiling for Medicare (an extra 0.9% applies above $200,000 for single filers), and the Social Security portion stops at the wage base, but for most solo earners, you hit it every year. The only legal way to reduce this is to stop paying self-employment tax on the portion of profit that exceeds a reasonable salary. That is where the S Corp election comes in, but it is not automatic, and it is not free.

When an LLC doesn't save you a dime in taxes

Here is the failure case that costs people real money: a single-member LLC is taxed as a sole proprietorship by default. You file Schedule C, you pay the same self-employment tax, and you get the same deductions. Forming an LLC gives you liability protection and a separation between personal and business assets, but it changes your tax bill by exactly zero dollars. The myth persists because multi-member LLCs are taxed as partnerships, which file Form 1065 and issue K-1s, but that does not reduce self-employment tax either, partners still pay it on their share of net earnings. The only way an LLC saves you a dime is if you make the S Corp election (Form 2553) within the deadline, and even then, you must pay yourself a salary. If you are currently a sole proprietor with an LLC but no S Corp election, your business taxes are identical to before. You are paying the same 15.3% on every dollar, and the LLC is just a legal shield, not a tax strategy.

The S corp reasonable salary rule

The IRS requires that S Corp owner-employees be paid a "reasonable salary" before any distributions. This is not a suggestion; it is a hard rule with audit consequences. If you take $80,000 in distributions and pay yourself $20,000 in salary, the IRS will reclassify the distributions as wages, add back the self-employment tax, and hit you with penalties and interest. The reasonable salary is based on what you would have to pay someone else to do your job, in your market, with your experience. For a freelance writer, that might be $60,000; for a consultant, $120,000; for a software developer, $150,000. The IRS publishes no fixed formula, but the general guidance is that the salary must be comparable to what you would pay an employee for the same work. The audit risk is real: the IRS has a specific program that targets S Corps with high distributions and low salaries, and they routinely win. You must run payroll, file Form 941 quarterly, pay unemployment tax (FUTA) if applicable, and file Form 940 annually. That administration costs money. As of this writing, Gusto charges $40 per month plus $6 per person for its Simple plan, and ADP quotes custom pricing you must request directly on adp.com; check both sites for current rates because these fees change. Subtract that annual cost from your projected tax savings before you decide.

Comparing take-home pay on a $100k profit

Let us run the numbers on a $100,000 profit. As a sole proprietor (or single-member LLC default), you pay 15.3% self-employment tax on the full $100,000: that is $14,130. You also get a deduction for half of that ($7,065), reducing your income tax, but you still owe roughly $14,130 in self-employment tax plus income tax on the remaining $92,935. Now, as an S Corp, you set a reasonable salary of $60,000. You pay 15.3% on that salary: $9,180. The remaining $40,000 is a distribution, which is not subject to self-employment tax. You still pay income tax on that $40,000, but you save the 15.3% on it: $6,120. That is the gross savings. Subtract the payroll administration cost. Gusto’s Simple plan starts at $40 per month plus $6 per person, and ADP requires a custom quote you get on their website; use those live figures, not a flat estimate, because your actual cost depends on the plan you pick. You must also pay unemployment tax on the salary (both federal and state, typically $500 to $1,000), and you must file an S Corp tax return (Form 1120-S), which costs an extra $500 to $1,000 in accounting fees. The real net savings is roughly $2,600 to $4,000, not the full $6,120. If your profit is $60,000, the salary must be at least $45,000 to be reasonable, and the savings shrink to under $2,000, often not worth the administrative hassle. The break-even is around $70,000 to $80,000 of net profit, below which the S Corp is usually not worth it.

How to calculate self-employment tax on your net income and lock in your number

Open your most recent Schedule C and find the net profit line. Multiply that number by 0.9235, then multiply the result by 0.153. That is your self-employment tax before the deduction. Write it down. Now open the IRS.gov Self-Employed Individuals Tax Center, locate the current-year SE tax rates and wage base, and confirm the cap on the Social Security portion because the IRS adjusts it annually. Do not rely on a flat percentage from a blog post. If your net profit exceeds the Social Security wage base, your effective rate drops on the excess, so your real bill changes. Bookmark that IRS page and revisit it every January before you make your S Corp election decision. If you use tax software, run a dummy return with your projected profit and compare the sole proprietor result to an S Corp scenario with a salary you document using a salary survey from the Bureau of Labor Statistics Occupational Outlook Handbook. Print that survey page and keep it in your tax file. The one sentence no competitor will give you is this: the S Corp election is not a tax loophole, it is a payroll compliance obligation that the IRS audits by comparing your W-2 to publicly available wage data for your job title and zip code.

Frequently Asked Questions

Can I switch from sole proprietor to S Corp in the middle of the year?

Yes, but the election must be filed within 2 months and 15 days of the date you want it to take effect, or by March 15 of the current year for a retroactive January 1 start. If you miss the deadline, you can request a late election under Revenue Procedure 2013-30, but you need a reasonable cause. Skip the mid-year switch. Wait until November, set a calendar reminder for December 1, and file Form 2553 with a January 1 effective date. Open a payroll account with your chosen provider during that same December window and run your first payroll in January. Arriving at this sequence late forces you to recharacterize prior months of owner draws, which creates extra accounting fees and potential payroll tax penalties.

Does the S Corp distribution count as earned income for my retirement plan?

No. For a solo 401(k) or SEP IRA, the contribution limit is based on your W-2 salary, not your distributions. If you pay yourself $60,000 in salary and take $40,000 in distributions, your retirement contribution limit is based on that $60,000. This is a hidden downside, you lose the ability to contribute a percentage of the full $100,000 profit to a retirement account, which can be a significant loss of tax-deferred growth.

What happens if I set my S Corp salary too low but not obviously unreasonable?

The IRS has a "facts and circumstances" test, and there is no safe harbor. If you pay yourself $50,000 when a comparable employee would earn $80,000, you are at risk. The IRS can reclassify the distribution as wages, add the full 15.3% self-employment tax, and assess a 20% accuracy-related penalty on the underpayment. Book a one-hour consultation with a CPA who specializes in S Corp payroll defense, not a general tax preparer, and bring three printed salary surveys for your role and metro area. Ask the CPA to write a one-page reasonableness memo you keep with your corporate minutes. Do not skip this step. The memo is your audit shield, and the IRS asks for it by name in an S Corp examination.