Tax Planning for Law Firms and Attorneys: SSTB Classification, S-Corp Structure, Trust Accounting, and Retirement Plans

Legal services is one of the original SSTBs named in IRC 199A(d)(2), and for high-earning attorneys, this classification is the most expensive single provision in the tax code because it eliminates the 20% QBI deduction that other pass-through business owners receive. An attorney earning $1 million in qualified business income loses a $200,000 deduction worth $74,000 in federal tax. There’s no workaround for the core legal services income: it is an SSTB at any scale. The planning focus for law firms therefore shifts entirely to reducing taxable income through S-Corp salary optimization, retirement plan maximization, and strategic use of the cash method of accounting. Solo practitioners and small firms that operate as sole proprietorships or general partnerships are leaving money on the table: the S-Corp election alone saves $15,000-$40,000 per year for a firm with $300,000+ in net income, and adding a defined benefit or cash balance plan can shelter $100,000-$300,000 of additional income from current taxation.

How do law firms minimize taxes?

What does an underpaid S-Corp salary risk for a solo attorney?

If the IRS decides a lawyer’s salary is unreasonably low, it can reclassify distributions as wages and assess the payroll tax, with interest and possibly penalties. For a solo attorney the IRS’s approach tends to point up: it looks at where the firm’s gross receipts came from, and in a practice without associates, most fees come from the lawyer’s own work.

The closest court case involves a professional firm. In Watson, an accountant who was the only shareholder and employee of his S-Corp paid himself $24,000 a year. The court set reasonable pay at $91,044 a year based on an expert’s market-value analysis.

At attorney income levels, a reclassified dollar costs less once salary passes the Social Security wage base ($176,100 for 2025, $184,500 for 2026). Above that, it’s 2.9% Medicare, plus the 0.9% Additional Medicare Tax on wages above $200,000 for single filers ($250,000 joint, $125,000 married filing separately). The employee alone pays that tax, and the thresholds aren’t indexed for inflation.

What is a single-member LLC and how is it taxed?

A single-member LLC is a legal entity with one owner. The IRS treats it as a disregarded entity by default, meaning it does not file its own return; income and expenses flow directly to Schedule C on the owner’s personal Form 1040. The LLC provides liability protection without adding a separate tax return. Self-employment tax applies to all net income, same as a sole proprietorship. You can elect S-Corp taxation by filing Form 2553, which keeps the LLC legal structure while changing the tax treatment to require a reasonable salary and allowing the remaining profit as a distribution free of FICA. State treatment varies: some states charge an annual LLC fee or franchise tax regardless of federal tax election.

Related guides:

• Tax Planning for Accounting Firms and CPA Practices: SSTB Classification, Partner Buy-In, and Practice Valuation

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