How to Calculate S Corp vs LLC Tax: The Core Math in 5 Steps
If you want to know how to calculate S corp vs LLC tax without relying on a black-box tool, start with one number: net profit. A single-member LLC by default is a disregarded entity, so you pay self-employment (SE) tax of 15.3% on 92.35% of that profit. Elect S corp status and you instead pay 15.3% payroll tax only on a reasonable W-2 salary, while the remaining profit flows out as distributions exempt from SE tax. For a $100,000 profit, the default LLC SE tax is about $14,130; an S corp with a $60,000 salary pays $9,180 in payroll tax, saving roughly $5,950 before income tax and QBI effects.
That slice of math is the heart of the comparison. The rest is layering in federal income tax, the 20% qualified business income (QBI) deduction, and real payroll compliance costs. Below I’ll walk through the exact worksheets I use, including a salary-split table and break-even checklist. If you’d rather cross-check the figures, our S-Corp vs LLC Tax Comparison Calculator automates the same formulas.
What “LLC S Corp” Actually Means (Clearing the PAA Confusion)
Many searchers type “LLC S corp” as if it’s a separate entity. It isn’t. An LLC is a state-law legal structure; “S corp” is a federal tax election made by filing Form 2553. The IRS allows an LLC to be taxed as an S corporation, which changes only the tax treatment, not the liability shield. This directly answers the people-also-ask question, “How are LLCs and S Corps taxed differently?”—the difference is purely about which tax regime applies to the same underlying profit.
When I filed my first Form 2553 for a consulting LLC in 2018, I assumed the election magically reduced my tax bill by 15% across the board. It didn’t. The tax code still requires a reasonable salary, and the payroll tax math only helps above a break-even threshold. That early misunderstanding cost me a late payroll setup penalty of $400 because I delayed running the first W-2 run.
The Thing Nobody Tells You About S Corp Savings
Most people don’t realize that the payroll tax saving on distributions is partially offset because your QBI deduction shrinks—wages paid by an S corp are not treated as qualified business income. In a default LLC, the entire net profit (minus SE tax adjustment) generates QBI. In an S corp, only the distribution portion does. That nuance is missing from almost every competitor calculator I’ve tested.
Step 1: Isolate Net Profit From Your Business Activity
Before any tax calculation, you must compute true net profit: gross receipts minus ordinary business expenses. For a sole-prop LLC this appears on Schedule C, line 31. For a multi-member LLC it’s on Form 1065, then allocated via K-1. I tell clients to strip out owner draws, personal expenses, and depreciation recapture before this step—those distort the comparison.
In my practice I build a simple spreadsheet column: Revenue, COGS, Operating Expenses, Depreciation. The bottom line is the figure we feed into both the LLC and S corp models. If your profit is below roughly $30,000, the administrative cost of payroll often eats the SE tax saving, a point we’ll quantify later.
Step 2: Default LLC Tax — Self-Employment Tax Formula
The default LLC (single-member) is taxed exactly like a sole proprietor. You owe SE tax to fund Social Security and Medicare. The statutory rate is 15.3%, but the law only applies it to 92.35% of net profit because the employer portion is deductible. The exact formula is: Net Profit × 0.9235 × 0.153.
For $100,000 profit: $100,000 × 0.9235 = $92,350. Multiply by 0.153 = $14,129.55. That is your SE tax. The Schedule SE instructions confirm this 92.35% factor, which many simplified calculators ignore.
How Much Tax Does a Default LLC Pay? (PAA Answer)
Answering “How much tax does an LLCs corp pay?” requires separating entities. A default LLC pays SE tax on all profit plus ordinary federal income tax on profit reduced by half the SE tax. Using 2024 brackets, a single filer with $100k profit and $14,130 SE tax gets $7,065 deductible, leaving $92,935 taxable income. At 22% marginal, federal income tax ≈ $12,894 (including standard deduction phase). Total ≈ $27,024 before QBI.
QBI then cuts that. The 20% deduction applies to $100,000 QBI (not reduced by SE tax), giving $20,000 deduction. Taxable income drops to $72,935, lowering income tax to about $9,200. Total with QBI ≈ $23,330. This is the baseline every S corp comparison must beat.
Why the 92.35% Factor Matters in Manual Math
If you skip the 92.35% step and just take 15.3% of full profit, you overstate SE tax by $1,530 on $100k. That error cascades into income tax because the deductible half is wrong. I’ve seen DIY spreadsheets overpay estimated taxes all year because of that omission. Precision here is what separates a real calculation from a guess.
Step 3: S Corp Salary vs Distribution Split and Payroll Tax
An S corp election requires the business to pay you a W-2 salary deemed “reasonable” by IRS standards. Only that salary faces the 15.3% payroll tax (split employer/employee). Remaining profit is distributed as dividends, escaping SE tax. To model this, use our Payroll Tax Calculator for exact splits, but the manual formula is simply Salary × 0.153.
Reasonable salary is not a number you invent. The IRS looks at industry data, your role, and hours worked. For a $100k consulting profit, a $60k salary is defensible; $30k is risky. When I advised a freelance designer, we set $55k salary based on Bureau of Labor stats, avoiding an audit trigger.
Salary / Distribution Split Table for $100k Profit
| Salary | Distribution | Payroll Tax (15.3%) | SE Tax on Full $100k | Payroll Tax Saving |
|---|---|---|---|---|
| $40,000 | $60,000 | $6,120 | $14,130 | $8,010 |
| $50,000 | $50,000 | $7,650 | $14,130 | $6,480 |
| $60,000 | $40,000 | $9,180 | $14,130 | $4,950 |
| $70,000 | $30,000 | $10,710 | $14,130 | $3,420 |
The table shows raw payroll tax saving before income tax. Notice the saving shrinks as salary rises. But salary too low invites penalties. The sweet spot is usually 50–70% of profit for service businesses.
The Social Security Wage Base Edge Case
Most people forget the 15.3% payroll tax is really 12.4% Social Security (capped at $168,600 for 2024) plus 2.9% Medicare (uncapped, plus 0.9% surtax over $200k single). If your salary exceeds the cap, the payroll tax rate on the excess drops to 2.9% (or 3.8%). That means high-earning S corps save even more on distributions above the cap—a detail missing from basic tools.
Step 4: The QBI 20% Deduction Math (How S Corps Get It)
The Section 199A deduction lets pass-through owners deduct up to 20% of qualified business income. According to the IRS QBI guidance, the deduction applies to income from a qualified trade or business, but explicitly excludes wages paid to an S corp owner. This answers the PAA: “How does an S Corp get a 20% tax deduction?”—it gets it on the distribution portion, not the salary.
For the default LLC, QBI = net profit ($100k). Deduction = $20k. For an S corp with $60k salary and $40k distribution, QBI = $40k, deduction = $8k. So the S corp loses $12k of QBI base. However, the salary itself is deducted by the corporation, reducing pass-through profit. The net effect must be computed in Step 5.
QBI Phase-Out and Specified Service Trap
If you’re in a specified service trade (law, health, consulting), QBI phases out between $191k–$241k (single, 2024). I’ve seen a $230k earner get zero QBI as a default LLC, making S corp election less valuable because the 20% lever is gone anyway. Non-service businesses can use the 20% even at high income if they stay under the wage limit formula. This is an advanced edge case beginners miss.
Step 5: Combine Income Tax, Payroll/SE Tax, and QBI for Total Liability
Now we total everything. Assume single, standard deduction $14,600, 22% marginal bracket. Default LLC: Profit $100k, half SE $7,065 deductible, QBI $20k deductible. Taxable income = $100k – $7,065 – $20k – $14,600 = $58,335. Income tax ≈ $6,600. Add SE $14,130 = $20,730 total.
S corp with $60k salary, $40k distribution: Salary taxable $60k (minus half payroll $4,590 deductible? Actually payroll tax is deducted on 1040 via Schedule 1, but simplification: taxable wage $60k). Distribution $40k. QBI = $40k, deduction $8k. Total pass-through income $100k same, but QBI smaller. Taxable income = $100k – $4,590 – $8k – $14,600 = $72,810. Income tax ≈ $9,200. Add payroll $9,180 = $18,380 total. Saving ≈ $2,350 after QBI drag.
The raw payroll saving was $4,950; QBI erosion ate $2,600 of it. That’s the honest trade-off. Run your own numbers with the same sequence and you’ll see why a calculator that hides QBI lies by omission.
Multi-Member LLC vs S Corp Election: Different K-1 Paths
A multi-member LLC default is a partnership. Each member pays SE tax on their distributive share (subject to 92.35% factor). Elect S corp and each member must take W-2 wages; remaining profit is distributions on K-1. The SE tax saving applies per member, but payroll must cover all working owners.
I handled a 2-member web agency with $300k profit. As partnership, each paid SE on $150k. As S corp, we set each salary $90k, distributions $60k. Combined payroll tax dropped from ~$42k to ~$27k. But we added $1,200 payroll service cost and had to file 1120-S. The manual calc must include those fixed costs.
Allocations and Built-In Gains
S corp ownership must match distribution ratios; partnerships can special-allocate. If you have unequal capital, the S corp election may force pro-rata splits that hurt one member. Also, converting appreciated assets triggers built-in gains tax for 5 years. That’s a landmine no PAA answer mentions.
Break-Even Checklist and Decision Matrix
Use this framework I call the “S Corp Switch Matrix.” List profit, reasonable salary, payroll cost, state tax, QBI phase. If (SE tax on full profit) – (payroll tax on salary) – (payroll admin $1k–$2k) – (lost QBI value) > 0, switch. For $100k example: $14,130 – $9,180 – $1,500 – $2,600 = $850 positive, so mild win.
Checklist: (1) Profit > $30k. (2) You can defend salary via industry data. (3) Not fully phased out of QBI if service business. (4) State doesn’t punish S corps (CA 1.5% net income fee). (5) You’ll run payroll quarterly. If any fail, stay default LLC.
Salary Split Decision Rule
Set salary at 60% of profit for service solo shops; 40% if you have substantial business assets and support staff. Document the rationale in a one-page memo. In an audit, the memo beats a spreadsheet.
State Tax Twists and Less-Obvious Edge Cases
Federal math is half the story. California charges S corps a 1.5% fee on net income plus $800 min franchise tax, wiping savings for small profits. New York requires S corp filers to also file state CT-3. Some states (e.g., Tennessee) tax distributions differently. I’ve modeled NJ clients where state tax erased 70% of federal payroll saving.
Another edge: S corp losses pass through but can’t exceed basis. Default LLC losses also need basis, but S corp stock basis tracking is more rigid. If you inject capital late, you may not deduct a loss that year—a trap for new startups.
Medicare Surtax Interaction
The 0.9% additional Medicare tax applies to wages over $200k. In an S corp, only salary triggers it; distributions escape. For a $250k earner, keeping $150k as distribution avoids $1,350 surtax. That’s a high-income sweetener the basic “15.3%” talk misses.
When an S Corp Election Is the Wrong Move
Be honest: if profit is volatile under $25k, the payroll admin and 1120-S filing cost (~$500–$1,500 annually) outweigh tax saved. If you’re a real estate investor using pass-through losses, S corp restrictions on basis and passive activity can hurt. I keep some clients as default LLC deliberately for simplicity.
Also, if you plan to raise venture capital, VCs dislike S corps due to shareholder limits (max 100, only US persons). An LLC or C corp fits better. The election is irreversible for 5 years without IRS consent, so the calculation isn’t just math—it’s strategy.
Putting the Manual Calculation to Work
Open a spreadsheet. Column A: net profit. Column B: default LLC SE tax = A*0.9235*0.153. Column C: proposed salary. Column D: payroll tax = C*0.153. Column E: QBI default = A*0.20; QBI S corp = (A-C)*0.20. Subtract the deduction difference from the payroll saving. If positive after $1,500 admin, elect.
I still run this by hand before touching any software. The exercise reveals whether a client’s “huge S corp saving” is real or an artifact of ignored QBI. Do the math line by line, and you’ll know exactly how to calculate S corp vs LLC tax for your specific situation—not a generic promise.