How a Solo Consultant Cut Their Effective Tax Rate by 11 Points in 18 Months

How a Solo Consultant Cut Their Effective Tax Rate by 11 Points in 18 Months

Filing as a sole proprietor when you're earning $280,000 a year is one of the most expensive decisions a self-employed person can make. Not because sole proprietorship is wrong for everyone — but because at that income level, the tax math has structurally better answers.

This is the case of a solo management consultant who was leaving roughly $30,000 per year on the table, and how CPA on Fire fixed it in three moves.

The Starting Point: $280K, Sole Proprietor, 31% Combined Rate

The client was a management consultant earning $280,000 per year in net self-employment income. No employees. No partners. Full Schedule C filer.

At that income level, sole proprietorship carries a specific tax burden that most people undercount. There's federal income tax — at $280K of net SE income, the effective rate on that top income puts a significant portion into the 32% and 24% brackets. And then there's the self-employment tax.

Self-employment tax runs at 15.3% on the first $176,100 of net SE income (2026 rate — the Social Security wage base adjusts annually) and 2.9% on everything above that. The consultant was paying SE tax on the full $280,000 of net income. That's $33,915 in SE tax before a dollar of income tax.

Combined federal effective rate: 31%.

That number is not unusual for a sole proprietor at this income level. It's also not necessary.

Step One: The S-Corp Election

The first move was an S-corp election.

An S-corp does not, by itself, reduce income tax. What it does is change how self-employment tax applies to the income.

As a sole proprietor, every dollar of net profit is subject to SE tax. As an S-corp owner, only the W-2 salary you pay yourself is subject to employment tax (the employer equivalent of SE tax). The remaining profit flows as a distribution and is not subject to employment tax.

CPA on Fire established a reasonable salary of $130,000 for the consultant's S-corp. That figure was benchmarked to what the market pays a management consultant at that billing rate — a number the IRS requires to be defensible and consistent with industry compensation.

With a $130,000 salary and $150,000 in distributions, the employment tax base dropped by $150,000. The SE tax savings on $150,000 of income removed from the employment tax base: approximately $11,500 per year.

That one structural change pays for a year of quality CPA services. Repeatedly.

Step Two: QBI Deduction Optimization

The Tax Cuts and Jobs Act created the Section 199A qualified business income deduction — 20% of qualified business income for eligible pass-through entities. The OBBBA has now made that deduction permanent.

As a sole proprietor, the client had technically been eligible for the QBI deduction. But there's a wrinkle: the QBI deduction on an S-corp is calculated on the pass-through income, which is the distribution amount after the reasonable salary is excluded.

With the S-corp structure in place, the QBI deduction applied to $150,000 in qualifying distributions. A 20% deduction on $150,000 reduces taxable income by $30,000.

Management consulting can be classified as a specified service trade or business (SSTB) depending on how the services are characterized. CPA on Fire reviewed the client's engagement structure and documented the non-SSTB elements of the practice — a fact-specific analysis that determines whether the full QBI deduction is available. Verify this with your own CPA; the answer depends on your specific service and income level.

The QBI deduction on the $150,000 in distributions: $30,000 reduction in taxable income, worth approximately $9,600 in federal income tax at this client's marginal rate.

Step Three: Solo 401(k) Through the S-Corp

With the S-corp W-2 salary established at $130,000, the third move was maximizing retirement contributions.

A solo 401(k) allows contributions in two buckets:

Employee elective deferrals: Up to $23,500 in 2026 (verify the current limit at publish time; this adjusts annually for inflation). These reduce W-2 income.

Employer profit-sharing contributions: Up to 25% of W-2 compensation. At a salary of $130,000, that's $32,500 in additional deductible contributions.

Combined: $56,000 in annual retirement contributions, all of which reduce taxable income.

The tax savings on $56,000 of contributions at the client's effective marginal rate: approximately $17,900.

The contributions don't disappear — they become retirement assets. But they reduce the current-year tax bill while building a balance that compounds tax-deferred until withdrawal.

The Outcome: 31% Down to 20%, on the Same Gross Income

Layering these three strategies together:

• S-corp election: ~$11,500 in SE tax savings
• QBI deduction: ~$9,600 in income tax savings
• Solo 401(k): ~$17,900 in income tax savings

Total annual tax reduction: approximately $39,000.

Combined federal effective rate: approximately 20%.

The 11-point drop — from 31% to 20% on the same $280,000 in gross income — reflects the compounding effect of strategies that work better together than any one of them does alone. The S-corp election enables the QBI optimization. The QBI optimization and the S-corp salary together determine how much of the solo 401(k) benefit flows through.

The total cost of the S-corp structure (CPA fees, payroll administration, S-corp tax return) runs approximately $5,000–8,000 per year. The strategy produces savings that dwarf that number in year one and every year after.

With the OBBBA permanently extending the QBI deduction, these savings are no longer subject to annual uncertainty. The planning payoff period for structural decisions is now measured in decades, not years.

What Solo Consultants at $150K+ Should Know

If you're self-employed and earning more than $150,000 per year as a sole proprietor or single-member LLC, the question isn't whether an S-corp election makes sense. The question is why you haven't done it yet.

The S-corp election is not exotic planning. It's the baseline.

Above the S-corp baseline, the QBI deduction and solo 401(k) are the next-level levers. Neither requires complex structures. Both require a CPA who understands the interaction between them and how to document the reasonable salary in a way that withstands scrutiny.

The IRS does audit S-corp owners who pay unreasonably low salaries. The documentation matters. The salary benchmark needs to be defensible. This is where working with a CPA who specializes in self-employed and small business clients earns its cost.

If you're a solo consultant filing as a sole proprietor and earning more than $150K, your tax situation has better answers. The most reviewed CPAs for self-employed professionals on Sam's List have run this analysis hundreds of times.

Find a CPA for self-employed professionals on Sam's List or view the CPA on Fire profile.

Figures in this case study are illustrative. Verify all details with the featured firm before publishing.