Self-Employment Tax Explained: Why You're Paying 15.3% (And How to Legally Pay Less)

The bill that catches every new trades owner off guard

Every year, a new trades business owner sits across from me at tax time with the same look on their face. They had a great year. They made $120,000 in profit. They've already paid quarterly estimates. And somehow they still owe another $8,000.

The question is always some version of: "How is this possible? I already paid taxes."

The answer is almost always: self-employment tax.

If you've never been self-employed before, you've never paid this tax directly — your employer paid half of it for you, invisibly, your whole working life. Now that you're the employer, you're paying the whole thing. And it's a big number.

What is self-employment tax?

Self-employment tax is the way the IRS collects Social Security and Medicare taxes from people who don't have an employer withholding it for them.

When you work a W-2 job, here's how it works:

• You pay 6.2% Social Security + 1.45% Medicare = 7.65% out of your paycheck
• Your employer pays another 6.2% + 1.45% = 7.65% on top of your wages
• Total: 15.3% going to FICA (Social Security + Medicare)

When you're self-employed, you ARE the employer. So you pay both sides.

That's where the 15.3% comes from. It's not a punishment for being self-employed — it's just the same FICA tax everyone pays, but you can see all of it. Per the IRS self-employment tax guidance, this is reported on Schedule SE with your Form 1040.

The 2026 details

Here's how the 15.3% breaks down:

• Social Security: 12.4% on the first $176,100 of net self-employment earnings (this cap adjusts annually for inflation; verify the current figure on the SSA wage base page)
• Medicare: 2.9% on ALL net self-employment earnings, no cap
• Additional Medicare Tax: 0.9% on earnings over $200K (single) / $250K (married filing jointly)

For most trades business owners, you'll hit the Social Security cap in a good year and then continue paying just the 2.9% Medicare on additional profit.

Real math: what this actually costs

SE tax alone on a $200K business is nearly $28,000. That's about the cost of a halfway decent work truck — every year — just for the privilege of being self-employed.

The half-deduction "consolation prize"

The IRS lets you deduct half of your SE tax as an "above-the-line" adjustment on your personal return. This reduces your income tax somewhat, but it doesn't reduce the SE tax itself.

On $100K of profit:

• SE tax paid: $15,300
• Half deductible against income: $7,650
• Tax savings from deduction (at, say, 22% bracket): ~$1,683

Helpful, but not exactly life-changing when the bill was $15,300 to start.

Why does this tax even exist?

A fair question. Two reasons:

1. Social Security and Medicare are funded by FICA taxes. Everyone who earns income from work is supposed to contribute, whether they're an employee or self-employed.
2. Without SE tax, self-employed people would skip out on the system. Then they'd hit retirement age with no Social Security benefits and no Medicare eligibility.

You're not paying SE tax to punish entrepreneurship. You're paying it to participate in Social Security and Medicare like everyone else.

The three legitimate ways to reduce self-employment tax

Now the part you actually came for. There are three legal ways to reduce your SE tax burden:

1. Maximize legitimate business deductions

SE tax is calculated on your net profit — revenue minus deductible expenses. Every legitimate deduction you take reduces both your income tax AND your SE tax.

Some of the biggest ones trades businesses miss:

• Vehicle expenses — Mileage at 70¢/mile, or actual expenses
• Section 179 — Full deduction on equipment and qualifying vehicles in the year placed in service
• Home office — A dedicated space for admin/scheduling/bidding qualifies
• Self-employed health insurance premiums — Deductible above-the-line
• Retirement contributions — SEP-IRA or Solo 401(k) contributions can reduce taxable income significantly
• Tools, supplies, software, training, licensing, insurance — All deductible if ordinary and necessary

If your books are sloppy and deductions are getting missed, this is the cheapest fix on the list. Full guide: The Complete Tax Deduction Guide for HVAC, Plumbing & Electrical Contractors

2. Elect S-Corporation status

This is the big one. S-Corp election is specifically designed to reduce the SE tax burden by reclassifying part of your income.

Here's how:

• As a sole prop / single-member LLC: ALL profit is subject to 15.3% SE tax.
• As an S-Corp: You pay yourself a reasonable salary through payroll. Salary gets payroll tax (which is effectively the same 15.3%). But profits above your salary come out as distributions — and distributions are not subject to SE tax.

Even after the cost of payroll services (~$500–$1,500/year) and an S-Corp tax return (~$650–$1,200), you're netting $8,000–$10,000+ in real savings.

The full breakdown of when S-Corp makes sense (and when it doesn't): Sole Prop vs. LLC vs. S-Corp for Trades Businesses.

3. Fund a SEP-IRA or Solo 401(k)

Retirement contributions reduce your taxable income — and for SEP-IRAs and Solo 401(k)s, they reduce the income that's subject to SE tax (with some nuance depending on entity type).

SEP-IRA:

• Contribute up to 25% of net self-employment earnings
• 2026 cap is around $70,000
• Easy to set up, low maintenance
• Best for owners with no employees (otherwise you have to contribute for them too)

Solo 401(k):

• Contribute up to ~$23,500 as the "employee" portion + up to 25% as the "employer" portion
• Same ~$70,000 total cap as SEP-IRA
• More flexibility, allows Roth contributions, allows loans
• Slightly more paperwork to set up

For a trades business owner pulling $200K+ in profit, maxing a Solo 401(k) or SEP-IRA can shelter $50K–$70K from taxes annually.

Retirement plans don't have to be funded until your tax filing deadline (including extensions). But you generally have to establish the plan by year-end to use it for that tax year (Solo 401(k) especially).

What about "writing off" my way out of SE tax?

This is where bad advice from social media meets real consequences.

You cannot deduct your way out of SE tax by inventing expenses. Personal vacations don't become deductible because you talked about work on the trip. Your kid's car isn't deductible because they sometimes ride to the job site with you.

The standard: An expense must be ordinary and necessary for your trade. The IRS doesn't define those terms with a checklist — they look at facts and circumstances.

Real, legitimate deductions can absolutely save you thousands. Made-up deductions can cost you tens of thousands in back taxes, penalties, and interest. The difference between the two is whether you can defend it.

Putting it all together

If you're a trades business owner getting hit hard by self-employment tax, here's the priority order:

1. Clean up your bookkeeping. Make sure every legitimate deduction is captured. This costs nothing extra and reduces SE tax dollar-for-dollar.
2. Run the S-Corp math. If your net profit is consistently above $50K-$60K, you're almost certainly leaving money on the table by staying a sole prop.
3. Set up a retirement plan. Even modest contributions add up fast.
4. Plan quarterly, not annually. SE tax surprises happen because owners don't project until April. Quarterly projections solve this.

Where Northbound fits

If running this math every quarter sounds like one more thing you don't have time for, that's exactly what we do.

Northbound's Growth plan includes quarterly CPA review reports — a written analysis of your P&L, your projected tax liability, and any moves you should make before year-end. It's the rhythm that turns "surprise tax bill in April" into "I knew this was coming, and I already planned for it."

We also handle the full S-Corp setup, reasonable compensation documentation, payroll, and the extra Form 1120-S filing — so if you're sitting on the line about electing S-Corp, the friction of running one isn't a reason to wait.

Book a free 30-minute discovery call →

Quick FAQ

Does self-employment tax replace income tax?

No. SE tax is in addition to federal income tax. You owe both.

Do I owe SE tax if I had a loss?

No. SE tax only applies to net positive earnings from self-employment.

I'm a single-member LLC. Do I still pay SE tax?

Yes. By default, single-member LLCs are taxed exactly like sole proprietors — full SE tax on all profit. The LLC only changes your legal status, not your tax status.

My spouse and I both work in the business. Does that change anything?

Possibly. There are specific rules for spousal partnerships ("qualified joint ventures") and how SE tax is allocated. Worth a conversation with a CPA.

I made $50,000 from my W-2 job and another $50,000 from my side trades business. Do I owe SE tax on all $100K?

No, only on the $50K of self-employment income. The W-2 wages already had FICA withheld.

I formed an LLC mid-year. Do I owe SE tax on the months before I formed it?

Yes. The LLC doesn't change your federal SE tax treatment (unless you elected S-Corp). Whether you were operating as a sole prop or under an LLC name, the SE tax math is the same.

Related reading

• The Complete Financial Playbook for Texas Trades Businesses
• Sole Prop vs. LLC vs. S-Corp: A Trades Owner's Guide
• The Complete Tax Deduction Guide for HVAC, Plumbing & Electrical Contractors
• Quarterly Tax Planning: The 90-Day System

All examples and tax figures are for illustrative purposes only and based on 2026 tax law as understood at the time of writing. Tax situations vary widely; always confirm current law and your specific facts with a qualified tax professional. Nothing in this article constitutes legal, tax, or financial advice for your specific situation.