Setting up as a CPA sole proprietor means carrying the full weight of the practice yourself: an active state license (and usually a separate firm permit), business registration where your name isn’t the business name, unlimited personal liability backed by insurance, and a tax life built around Schedule C, self-employment tax, and quarterly estimates. Get those right and the rest is refinement. Get any one of them wrong and you’re looking at license suspension, IRS penalties, or personal assets on the line.
Licensing That Keeps You Legal
Your individual CPA license is the foundation, but it isn’t the only credential to track. Many state boards require a separate firm permit or firm registration even for a one-person practice, with its own renewal cycle and fee. Skipping the firm registration is a common oversight for new practitioners and can draw board discipline even while your personal license is current.
Continuing Professional Education
Every state requires CPAs to complete CPE to renew. The typical requirement is 40 hours per year, though many states measure compliance over a two- or three-year reporting period with cumulative totals ranging from 80 to 120 hours. A portion must cover ethics, usually between two and eight hours per cycle depending on the state. Missing the deadline can suspend or revoke your license, which immediately shuts down your ability to practice.
Preparer Tax Identification Number
If you prepare federal returns for compensation, the IRS requires a valid PTIN. Renewal is annual, and the current fee is $18.75.1Internal Revenue Service. PTIN Requirements for Tax Return Preparers To obtain or renew a PTIN, you must attest that your own personal and business filings are current and any taxes owed have been paid or are under an approved payment plan.2Internal Revenue Service. Frequently Asked Questions: PTIN Application/Renewal Assistance Easy to let slip in a busy January, and practicing without a valid PTIN triggers IRS penalties.
Business Registration and Tax ID
Practicing under your own personal name, most states don’t require a separate business name filing beyond your state board registration. Use anything else and you’ll need a fictitious name statement or DBA registration with your county or state. Some state boards also have their own fictitious name permit on top of the local filing.
For tax ID, a sole proprietor can use a Social Security number to file returns and report income. Getting an EIN anyway is a smart move. The IRS requires one if you hire staff, operate a qualified retirement plan, or file excise tax returns.3Internal Revenue Service. Get an Employer Identification Number Even without those triggers, an EIN keeps your SSN off client documents and bank records, reducing identity theft risk.
Local business licenses or occupational privilege taxes vary widely by city and county, and some localities don’t require any. Check with your local government before you bill your first client.
Unlimited Personal Liability
The single biggest structural risk of a sole proprietorship is that there’s no legal wall between you and the business. If a client sues for malpractice, or the firm takes on debt it can’t pay, your personal bank accounts, home equity, and other assets are all reachable. That’s the sharpest difference from an LLC or professional corporation, which can at least partially shield personal assets from business claims.
Professional liability insurance, often called errors and omissions coverage, is the primary defense. Policies for CPA firms typically offer limits from $100,000 up to $10 million per claim, with most sole practitioners carrying between $500,000 and $5 million depending on client size and service type.4Accounting Today. The 2023 Accountants Malpractice Liability Insurance Buyers Guide CPAs who perform audits or forensic work generally pay higher premiums and should carry limits at the upper end. Premiums are driven by gross revenue, geographic location, and claims history.
Keeping business and personal finances separate won’t create a legal shield the way an LLC would, but it matters for two practical reasons. Clean records make it far easier to defend against inflated claims. And commingled finances are a red flag in any audit or legal proceeding, and they undermine your credibility as a financial professional. Use a dedicated business bank account and credit card for every firm transaction.
Federal Income Tax and Schedule C
All business income and expenses flow through Schedule C, attached to your personal Form 1040.5Internal Revenue Service. About Schedule C (Form 1040) Net profit lands on your individual return and is taxed at your ordinary income rate. There’s no separate business return, which keeps administration simple but means your business profit directly increases your personal tax bill.
Ordinary and necessary business expenses reduce that profit. For a CPA practice, the usual list includes CPE costs, professional dues to organizations like the AICPA or state societies, accounting and tax software subscriptions, office rent, utilities, and depreciation on equipment. If you pay for your own health insurance, you can also deduct the full cost of medical, dental, and vision premiums for yourself, your spouse, and your dependents as an adjustment to income, as long as you aren’t eligible for coverage through another employer.6Internal Revenue Service. Instructions for Form 7206
Home Office Deduction
If you use part of your home exclusively and regularly as your principal place of business or as the place where you meet clients, you can deduct a share of your housing costs. The IRS is strict about the exclusive-use test: the space must be used only for business, not a guest room that doubles as an office. A separate detached structure like a converted garage qualifies if you use it exclusively and regularly for business, even if you don’t meet clients there.7Internal Revenue Service. Publication 587 – Business Use of Your Home
Two calculation options exist. The simplified method allows $5 per square foot of dedicated business space, capped at 300 square feet for a top deduction of $1,500.8Internal Revenue Service. Simplified Option for Home Office Deduction The regular method calculates actual expenses like mortgage interest, property taxes, insurance, and utilities proportional to the business-use percentage of your home. More recordkeeping, but often a larger deduction if you have real dedicated office space.
Self-Employment Tax
Self-employment tax is what catches new sole proprietors off guard. As an employee, you paid 7.65 percent of your wages toward Social Security and Medicare, and your employer matched it invisibly. As a sole proprietor, you pay both halves: 15.3 percent total.9Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes) That’s 12.4 percent for Social Security and 2.9 percent for Medicare.
The Social Security portion only applies to net earnings up to $184,500 in 2026.10Social Security Administration. Contribution and Benefit Base Income above that ceiling is exempt from the 12.4 percent Social Security piece. The 2.9 percent Medicare tax has no cap. If your net earnings exceed $200,000 as a single filer or $250,000 filing jointly, an additional 0.9 percent Medicare tax applies to the amount above the threshold.9Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)
One partial offset: you can deduct half of your self-employment tax as an adjustment to gross income on Form 1040. That doesn’t reduce the SE tax itself, but it lowers the income subject to ordinary income tax.9Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes)
Quarterly Estimated Payments
With no employer withholding, you’re responsible for paying income tax and SE tax in quarterly installments. The requirement applies if you expect to owe $1,000 or more in federal tax after withholding and refundable credits.11Internal Revenue Service. Estimated Tax for Individuals You calculate and submit these using Form 1040-ES.12Internal Revenue Service. About Form 1040-ES, Estimated Tax for Individuals
The four payment deadlines for tax year 2026 are April 15, June 15, September 15, and January 15 of the following year. If a due date falls on a weekend or holiday, the deadline shifts to the next business day.13Internal Revenue Service. Estimated Tax
Missing or underpaying triggers a penalty calculated on the shortfall for each quarter. To stay safe, your total payments should equal at least 90 percent of your 2026 tax liability or 100 percent of your 2025 liability, whichever is smaller. If your 2025 adjusted gross income exceeded $150,000, that second number rises to 110 percent of your prior-year tax.11Internal Revenue Service. Estimated Tax for Individuals For a CPA in the first or second year of practice with income climbing fast, the prior-year safe harbor is usually the easier target to hit.
The Qualified Business Income Deduction
Section 199A lets sole proprietors and other pass-through owners deduct a percentage of qualified business income before calculating income tax.14Office of the Law Revision Counsel. 26 USC 199A – Qualified Business Income Originally set to expire after 2025, the deduction was extended for 2026 and beyond at 23 percent of qualified business income.
Here’s the catch. Accounting is classified as a “specified service trade or business” under the statute, so the deduction phases out and eventually disappears entirely as your taxable income rises.14Office of the Law Revision Counsel. 26 USC 199A – Qualified Business Income For 2026, single filers begin losing the deduction when taxable income exceeds roughly $201,750, and it’s fully eliminated above approximately $276,750. For joint filers, the phase-out range runs from about $403,500 to $553,500. Below the floors, a CPA sole proprietor takes the full deduction. Above the ceilings, the deduction is zero regardless of how much business income you earned.
The tax-planning stakes are real. A sole practitioner with $180,000 of taxable income could save over $9,000 through QBI, while one at $300,000 gets nothing. Maximizing retirement contributions is one of the most effective ways to keep taxable income inside the phase-out window.
Retirement Plans and HSAs
As a sole proprietor without employees, you have access to retirement vehicles that shelter significant income while building long-term wealth. The two most common are the SEP IRA and the solo 401(k).
A SEP IRA lets you contribute up to 25 percent of net self-employment earnings, capped at $72,000 for 2026.15Internal Revenue Service. SEP Contribution Limits Administration is minimal and there’s no annual IRS filing. The downside: all contributions are employer contributions based on a percentage of income, so you can’t front-load as aggressively at lower income levels.
A solo 401(k) offers more flexibility. You can defer up to $24,500 as the “employee” side of the plan, plus contribute up to 25 percent of net self-employment compensation as the “employer” profit-sharing piece, with the same $72,000 combined ceiling. If you’re between 60 and 63, enhanced catch-up contributions allow an additional $11,250 in employee deferrals. The solo 401(k) also offers a Roth option, which the SEP IRA does not. Trade-off: more paperwork, and plans with assets exceeding $250,000 require an annual Form 5500-EZ filing.
If you carry a high-deductible health plan, an HSA adds another tax-advantaged layer. For 2026, the contribution limit is $4,400 for individual coverage and $8,750 for family coverage, plus a $1,000 catch-up if you’re 55 or older. HSA contributions reduce your self-employment income, and qualified medical withdrawals are tax-free.
Peer Review Only If You Do Attest Work
If your practice includes audits, reviews, or compilation engagements where you provide assurance on financial statements, your firm must undergo peer review every three years.16AICPA & CIMA. Peer Review: A Vital Component in Audit Quality Sole practitioners who stick exclusively to tax preparation, consulting, or bookkeeping are generally exempt, though most boards want a signed statement confirming you don’t perform attest engagements. Watch for scope creep: a single compilation with assurance triggers the requirement for your entire practice.
Practicing Across State Lines
All 55 U.S. accountancy board jurisdictions recognize substantial equivalency under the Uniform Accountancy Act, so a CPA licensed in one state can generally practice in another without a full reciprocal license.17NASBA. Substantial Equivalency To qualify, your home-state license must meet the UAA baseline: 150 semester hours, the Uniform CPA Examination, and at least one year of qualifying experience. Mobility isn’t a free pass, though. Some jurisdictions require notification or a fee before you practice there, and definitions of what counts as “practicing” in a state, including remote work for clients located there, vary. Before taking on out-of-state clients, check with the board of accountancy in the client’s state.
Continuity Planning
This is the requirement most sole practitioners put off indefinitely, and it’s the one that matters most to clients if something happens to you. A practice continuation agreement is a written contract with another CPA or firm that ensures your clients are covered if you become disabled, die, or otherwise can’t continue.
These agreements typically take one of two forms: a one-on-one arrangement with another sole practitioner, structured as a buy-sell or cross-purchase, or a group arrangement where several CPAs back one another up. Some state CPA societies also run emergency assistance programs for practices left without a plan. At a minimum, the agreement should address valuation, client notification, transfer of work in process and receivables, disposition of workpapers, and a noncompetition clause, with separate protocols for temporary disability versus permanent transfer. Once it’s signed, tell your attorney, any staff, and your spouse so the process can actually work when it needs to.