Consulting Business Entity Structure: LLC vs S-Corp and the SSTB Problem

Independent consultants who earn more than $80,000-$100,000 in net profit should evaluate the S-Corp election. The math is straightforward: a sole proprietor pays 15.3% self-employment tax on all net profit (up to the Social Security wage base), while an S-Corp owner pays payroll tax only on the salary they draw, with the remaining profit flowing through as a distribution that is exempt from payroll tax. The complication for consultants is that consulting is classified as a Specified Service Trade or Business (SSTB) under IRC 199A, which means the 20% QBI deduction phases out and disappears as the owner’s taxable income exceeds $191,950 (single) or $383,900 (MFJ) for 2026.

How much does the S-Corp save in self-employment tax?

The savings depend on the gap between net profit and reasonable salary. The wider the gap, the larger the savings.

What’s a “reasonable salary” for a consultant?

The IRS requires that S-Corp shareholder-employees pay themselves reasonable compensation for the services they perform. There is no bright-line rule; it is a facts-and-circumstances determination. Factors the IRS considers:

The nature and extent of the services the shareholder provides. The compensation paid by comparable businesses for similar services. The time the shareholder devotes to the business. The shareholder’s education, training, and experience. The firm’s revenue and profitability.

For a solo consultant who does all the work (client development, project delivery, administration, billing), the reasonable salary should reflect what a full-time employee doing the same work would earn. For a management consultant billing $200-$400/hour, a salary of $80,000-$150,000 is typically defensible, depending on the market, the consultant’s experience, and the hours worked.

Setting the salary too low (for example, $40,000 for a consultant earning $300,000) invites IRS reclassification of distributions as wages, with back payroll taxes, interest, and penalties. Setting it too high eliminates the SE tax benefit of the S-Corp. The right number is somewhere in the middle, supported by market data.

How does the SSTB phase-out work?

The SSTB phase-out operates on a sliding scale:

Below $383,900 MFJ ($191,950 single): The full 20% QBI deduction is available, subject to the W-2 wage and UBIA limitations. For a solo consultant with no employees (only the owner’s W-2), the W-2 wage limitation is 50% of the owner’s salary. The QBI deduction cannot exceed this amount.

$383,900 to $533,900 MFJ ($191,950 to $266,950 single): The QBI deduction phases out linearly (the One Big Beautiful Bill Act widened this range from $100,000/$50,000 to $150,000/$75,000). At the midpoint of the range, 50% of the deduction is available. At the top of the range, the deduction is zero.

Above $533,900 MFJ ($266,950 single): The QBI deduction is zero. The SSTB status is irrelevant below the lower threshold and fatal above the upper threshold.

For consultants in the phase-out range, every dollar of additional taxable income reduces the QBI deduction. The effective marginal rate in the phase-out range is higher than the statutory rate because the lost QBI deduction adds to the tax cost. Strategies to stay below the threshold (retirement plan contributions, charitable contributions, timing of income) can preserve the deduction.

When does a C-Corp make sense for a consultant?

Rarely. A C-Corp pays tax at 21% on its income, and distributions to the shareholder are taxed again as qualified dividends (0%/15%/20%). For a consultant who extracts all income as compensation or dividends, the combined rate exceeds the pass-through rate.

The C-Corp can make sense in a narrow scenario: a consultant who retains earnings in the corporation (for expansion, working capital, or investment) and does not distribute them. The 21% corporate rate is lower than the top individual rate (37%), so retained earnings grow faster inside the C-Corp. But the consultant must eventually extract the earnings (as salary, dividends, or at liquidation), and the second layer of tax applies.

The accumulated earnings tax under IRC 531 imposes a 20% penalty on accumulated earnings beyond the reasonable needs of the business ($250,000 for most businesses). A solo consulting firm with no employees and no capital needs will have difficulty justifying accumulations beyond this threshold.

What about multi-consultant firms?

A firm with multiple consultants (2-10 partners or members) typically operates as a partnership or multi-member LLC taxed as a partnership. The partnership provides flexibility in profit allocation (senior partners can receive a larger share), buy-in structures (new partners can acquire a profits interest without immediate taxation under Rev. Proc. 93-27), and compensation design (guaranteed payments plus profit shares).

An S-Corp is less flexible for multi-owner consulting firms because of the single-class-of-stock requirement. All shareholders must receive distributions in proportion to ownership. For firms where compensation should reflect individual production (a common model in consulting), the partnership structure is superior.

The SSTB classification applies to the firm regardless of entity type. The QBI deduction phases out for each individual partner or shareholder based on their own taxable income, not the firm’s income.

Related guides:

• Marketing Agency Entity Structure: S-Corp, the Consulting SSTB Risk, and QBI Planning

• Bookkeeping Business Structure: S-Corp, SSTB Classification, and the QBI Limitation

• Consulting practice tax deductions, the deductions available once the entity is in place

• Retirement plans for consultants, how entity choice affects contribution limits and the salary-vs-distribution tradeoff

• Multistate tax and nexus for consultants, how remote work and client-state travel create filing obligations

• Succession planning and partner buyouts, structuring the exit to maximize capital gains treatment

• Coaching business tax deductions and the SSTB question, how the SSTB classification applies to life coaching, business coaching, and executive coaching

• Employee vs. contractor classification for consulting firms, how to classify subcontractors correctly and avoid misclassification penalties

• R&D tax credit for technology consulting firms, how the IRC 41 credit applies to custom software development and technical consulting

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.