To start a sole proprietorship in Colorado, you file a Statement of Trade Name with the Secretary of State for $20 if you want to operate under a business name other than your own, then collect the tax IDs and local licenses your work requires and open a separate bank account. There is no formation document to file for the business itself, because a sole proprietorship is not legally separate from you. Most of the work is on the tax and licensing side, not on registering the business.
Step 1: Pick a Name and Check It’s Available
You can operate under your own first and last name without any state filing. If you want a different business name — Colorado calls it a trade name, and you may hear it called a DBA — it has to be distinguishable from every other entity name already on file with the Secretary of State.1Colorado Revised Statutes. Colorado Code 7-90-601 – Distinguishable Name Run the free search on the Secretary of State’s business database before you commit.
Distinguishable means more than a punctuation tweak or adding a word like “company.” If “Peak View Design” is already registered, “Peak View Design Co.” won’t clear.
A Colorado trade name only protects the name inside Colorado’s business records. It does not give you trademark rights. If you plan to sell outside the state, search the U.S. Patent and Trademark Office database as well; a federal trademark gives nationwide ownership, while a state trade name just lets you do business under the name here.2United States Patent and Trademark Office. How Trademarks and Trade Names Differ
Step 2: File the Statement of Trade Name
Once the name clears, file a Statement of Trade Name through the Secretary of State’s online portal.3Colorado Secretary of State. File a Business Document You’ll provide your legal name, a mailing address, and the exact trade name.4Colorado Revised Statutes. Colorado Code 7-71-103 – Statement of Trade Name The fee is $20, and the filing typically appears in the public record right after submission.
Operating under your own legal name? Skip this step. There is no general “sole proprietorship registration” in Colorado, and the Statement of Trade Name is the only state-level filing that applies — only when the business name differs from yours.
One easy thing to forget: the trade name is not permanent. You renew it annually during the last three months it’s effective.5Colorado Revised Statutes. Colorado Code 7-71-105 – Renewal of Statement of Trade Name Miss the window and the name goes inactive, which opens the door for someone else to grab it.
Step 3: Get Your Tax IDs
As a solo operator with no employees, you can report income using your Social Security number. Getting a free Employer Identification Number from the IRS is still worth it. An EIN keeps your SSN off invoices and vendor forms, and you’ll need one anyway if you ever hire someone, open certain business accounts, or set up a Solo 401(k) or Keogh retirement plan.6Internal Revenue Service. Employer Identification Number The online application takes a few minutes.
If you’ll sell physical products in Colorado, you also need a sales tax license from the Colorado Department of Revenue before making any retail sales.7Department of Revenue – Taxation. How to Apply for a Colorado Sales Tax License It’s valid for two years and expires at the end of each odd-numbered year. The fee depends on when you apply: $16 between January and June of an even-numbered year, or $12 between July and December.8Department of Revenue – Taxation. Standard Retail License New accounts also owe a one-time $50 deposit with the application, so plan on roughly $66 for your first license.
Step 4: Check Local and Occupational Licenses
Colorado has no statewide general business license, but many cities and counties do. Denver, Aurora, Colorado Springs, and other municipalities each run their own licensing systems covering zoning, health and safety, and industry-specific rules. Fees vary widely by location and business type, so check with the city or county where you’ll operate.
If you’ll work from home, review your city’s zoning rules first. Residential zones commonly restrict home-based businesses in ways people don’t expect — rules about customer foot traffic, signage, parking, outdoor storage, and the share of the home used for the business. Some cities require a home occupation permit. Violations can bring fines or a shutdown order.
Certain professions also need a state occupational license from the Colorado Department of Regulatory Agencies (DORA). Accounting, real estate, cosmetology, contracting, and healthcare all fall under DORA. If your field is regulated, you need that credential on top of any local business license.
Step 5: Open a Business Bank Account
Nothing in the law forces a sole proprietor to have a separate bank account, but mixing personal and business money is one of the most common and most costly mistakes. Tracking income and expenses becomes a mess at tax time, and legitimate deductions get missed. Bring your filed Statement of Trade Name (if you have one) and your EIN or Social Security number to the bank and open a dedicated checking account in the business name. Run every business dollar through it from day one.
Taxes You’ll Owe as a Sole Proprietor
This is the part that catches most first-time sole proprietors. Your net business profit gets taxed twice over. First, self-employment tax of 15.3% covers both the employer and employee shares of Social Security (12.4%) and Medicare (2.9%).9Internal Revenue Service. Self-Employment Tax (Social Security and Medicare Taxes) The Social Security portion applies to net earnings up to $184,500 in 2026; the Medicare portion has no cap.10Social Security Administration. Contribution and Benefit Base Second, you pay regular federal income tax on the same profit, reported on Schedule C with your personal Form 1040. Colorado adds its flat 4.25% state income tax on your taxable income.
Nobody is withholding anything from your pay, so you send quarterly estimated payments to both the IRS and the Colorado Department of Revenue. Federal estimated payments for 2026 are due April 15, June 15, September 15, and January 15, 2027.11Internal Revenue Service. 2026 Form 1040-ES – Estimated Tax for Individuals Colorado follows the same schedule. Underpaying triggers an IRS penalty based on the amount owed, how long it stayed unpaid, and the current underpayment interest rate.12Internal Revenue Service. Underpayment of Estimated Tax by Individuals Penalty Colorado charges its own underpayment penalty. Set tax money aside throughout the year rather than scrambling each quarter.
Personal Liability and Insurance
The big trade-off of a sole proprietorship is unlimited personal liability. Because there’s no legal separation between you and the business, a lawsuit against the business is a lawsuit against you. A judgment can reach your home, car, savings, and other personal assets. That is the core difference between a sole proprietorship and an LLC or corporation, and it’s worth understanding clearly before you choose this structure.
Insurance is the main tool sole proprietors use to manage that risk. A general liability policy covers claims for bodily injury, property damage, and related legal costs arising from your operations.13U.S. Small Business Administration. Get Business Insurance If you give professional advice or provide specialized services, look at professional liability coverage (errors and omissions) as well, since general liability typically excludes claims of negligence, bad advice, or substandard work. Neither policy is legally required for a solo operation with no employees, but a single uncovered lawsuit can wipe out years of savings.
If You Hire Employees or Contractors
Adding even one employee triggers a stack of new obligations. Colorado requires every employer to carry workers’ compensation insurance, whether the employee is full-time, part-time, or a family member.14Colorado Division of Workers’ Compensation. Workers’ Compensation Insurance Requirements You’ll need an EIN if you don’t have one, and you’ll withhold federal income tax, Social Security, and Medicare from each paycheck. Federally, you must verify identity and work eligibility on Form I-9 within three business days of the start date,15USCIS. Completing Section 2, Employer Review and Attestation pay Federal Unemployment Tax on the first $7,000 of each employee’s wages,16Employment and Training Administration. FUTA Credit Reductions and keep detailed payroll records for at least three years.17eCFR. Part 516 – Records to Be Kept by Employers
Hiring contractors instead? Note the reporting change. Starting in 2026, you file a Form 1099-NEC for any contractor paid $2,000 or more during the year, up from the old $600 threshold.18Internal Revenue Service. Publication 1099 General Instructions for Certain Information Returns The threshold begins adjusting for inflation in 2027.
Keeping Your Sole Proprietorship Active
A few things recur beyond quarterly tax payments. If you filed a Statement of Trade Name, renew it annually in the last three months before it expires.5Colorado Revised Statutes. Colorado Code 7-71-105 – Renewal of Statement of Trade Name Your sales tax license renews every two years, at the end of each odd-numbered year.8Department of Revenue – Taxation. Standard Retail License
Business personal property tax surprises many sole proprietors. If you own taxable business equipment such as computers, furniture, tools, or machinery, you file a personal property declaration schedule with your county assessor by April 15 each year.19Colorado Division of Property Taxation. Personal Property Frequently Asked Questions All business personal property in Colorado is taxable unless a specific exemption applies, and fully depreciated assets stay on the rolls. Skip the filing and the assessor estimates the value for you, which rarely helps.
Keep clean records from day one. You’ll need them for Schedule C, for sales tax reporting if that applies, and to back up deductions if the IRS or the Colorado Department of Revenue asks questions. The sole proprietors who hit real trouble in year one are almost always the ones who let record-keeping slide.