7 Mistakes Small Law Firms Make in Their First Year

2026-08-21

Avoid common tax pitfalls in your first year of practice. Learn the 7 mistakes small law firms make and how to fix them with practical steps.

Starting a small law firm is exciting, but the first year is also when tax mistakes can quietly pile up. Many new owners focus on clients and billable hours, then face surprises at tax time. Here are the seven most common tax mistakes small law firms make in their first year, and how to avoid each one.

1. Mixing Personal and Business Finances

Using the same bank account or credit card for personal and business expenses is the fastest way to create tax headaches. It makes it nearly impossible to track deductible expenses accurately, and it can trigger an audit if the IRS sees excessive personal spending in a business account.

What to do this week: Open a separate business checking account and a business credit card. Use them exclusively for firm expenses. If you have already mixed funds, go through your statements and categorize every transaction, then set a rule to stop mixing going forward.

2. Choosing the Wrong Business Structure

Many solo attorneys default to a sole proprietorship, but that offers no liability protection and can lead to higher self-employment taxes. An LLC or S-corp may be better, but the right choice depends on your revenue and state.

What to do this week: Consult a CPA or tax attorney who works with law firms. Compare structures: sole proprietorship (no filing fee, but unlimited personal liability), LLC (state filing fee typically $50-$500, pass-through taxation), S-corp (additional payroll requirements, but can reduce self-employment tax on income above a reasonable salary). For most small firms earning over $60,000, an S-corp can save $3,000-$8,000 annually, but it requires payroll setup and quarterly filings.

3. Ignoring Quarterly Estimated Taxes

If you are self-employed or own a pass-through entity, you must pay estimated taxes quarterly. Missing these payments leads to penalties and interest, even if you pay everything by April 15.

What to do this week: Calculate your expected annual income and tax liability. Use IRS Form 1040-ES or work with your accountant. Set reminders for April 15, June 15, September 15, and January 15. If you are unsure, pay at least 100% of last year’s liability (110% if your income is over $150,000) to avoid penalties.

4. Not Tracking Deductible Expenses from Day One

Law firms have many deductible expenses: office rent, software, continuing legal education (CLE), bar dues, malpractice insurance, client meals, and home office costs. Missing these deductions means paying more tax than necessary.

What to do this week: Set up a bookkeeping system, whether it’s QuickBooks, Xero, or a simple spreadsheet. Categorize every expense as you incur it. Keep receipts for anything over $75. For home office deductions, measure the square footage and calculate the percentage of your home used exclusively for business (simplified method: $5 per square foot, up to 300 square feet).

5. Failing to Separate Retainer Funds

Client retainers are not income until you earn them. If you deposit retainers into your operating account and spend them, you may owe tax on money you haven’t earned yet, and you risk commingling client funds, which violates ethics rules.

What to do this week: Open a separate IOLTA (Interest on Lawyers’ Trust Accounts) account for retainers. Transfer funds to your operating account only as you bill for work performed. Track your unearned retainer balance monthly. This keeps your tax liability accurate and protects your license.

6. Overlooking Payroll Taxes for Employees

If you hire staff, even part-time, you must withhold and pay payroll taxes. New owners often miss deadlines or misclassify employees as independent contractors, leading to back taxes and penalties.

What to do this week: If you have employees, register for an EIN and state tax IDs. Use a payroll service like Gusto or ADP (cost: $40-$100/month plus per-employee fees). If you use contractors, get a W-9 and issue 1099-NECs at year-end for payments over $600. Misclassification can cost thousands in back taxes, so when in doubt, consult a professional.

7. Not Planning for Retirement or Health Insurance Deductions

Many new owners skip retirement plans because they think they can’t afford them, but SEP IRAs and solo 401(k)s offer significant tax deductions. Similarly, health insurance premiums are deductible for self-employed individuals, but only if you are not eligible for an employer-sponsored plan.

What to do this week: Open a SEP IRA or solo 401(k) before year-end. Contributions are tax-deductible up to 25% of net earnings (max $69,000 in 2026). For health insurance, pay premiums from your business account and deduct them on your personal return. Even a small contribution reduces your taxable income now.

FAQ

Q: Can I deduct startup costs for my law firm? A: Yes, you can deduct up to $5,000 in startup costs in your first year, with the rest amortized over 180 months. This includes market research, office setup, and initial legal fees.

Q: What if I miss a quarterly estimated tax payment? A: You will owe a penalty based on the amount and time late. File and pay as soon as possible to minimize penalties. The IRS may waive penalties if you show reasonable cause, but it’s not automatic.

Q: Should I use an accountant or tax software? A: For most small firms, a CPA who specializes in law firms is worth the cost ($500-$2,000 for tax prep). They catch deductions and avoid errors that software might miss. Software like TurboTax Self-Employed costs $100-$200 but lacks personalized advice.

Q: How long do I need to keep tax records? A: Keep all tax returns and supporting documents for at least 3 years, but 7 years is safer if you have unreported income or large deductions. Retain client trust account records for at least 5 years per ethics rules.

The bottom line

The first year of a law firm is a learning curve, but tax mistakes are avoidable. Separate your finances, choose the right structure, pay estimated taxes, track deductions, handle retainers correctly, manage payroll, and plan for retirement. Take one action this week: open a separate business account or schedule a consultation with a CPA. These steps will save you money and stress at tax time, and they set the foundation for a financially healthy practice.