How to File a DBA in Delaware (2026)

What Is a DBA and Why Delaware Requires One

A DBA (Doing Business As), also called a fictitious name or assumed name, is a legal registration that allows you to operate a business under a name different from your legal entity name. In Delaware, sole proprietors must file a DBA—it is not optional. According to Delaware's business formation data, sole proprietorships require DBA filing. LLCs also must file a DBA if they conduct business under any name other than the one on their Certificate of Formation. The DBA creates a public record linking your assumed name to your legal entity, protecting your business identity and preventing others in your county from using the same name.

When You Must File a DBA in Delaware

You are required to file a DBA if any of the following apply:

Sole proprietors must file a DBA regardless of whether you use your personal name. Delaware's business formation data explicitly states that sole proprietorships require a DBA filing.

LLCs and corporations must file a DBA if you operate under any name other than your registered entity name. For example, if your LLC is "Smith Consulting LLC" but you advertise as "Smith Business Solutions," you need a DBA for the assumed name.

Multiple locations require separate DBA filings in each county where you conduct business. If you operate in New Castle, Kent, and Sussex counties, you file three separate DBAs—one per county.

You do not need a DBA if you operate solely under your legal entity name as it appears on your formation documents.

Where to File Your DBA in Delaware

DBAs are filed at the county level, not with the Delaware Division of Corporations. This is a critical distinction: unlike your LLC Certificate of Formation or corporation Charter, which go to the state, your DBA goes to your county.

Filing location by county:

New Castle County: New Castle County Prothonotary, (302) 395-8000
Kent County: Kent County Prothonotary, (302) 744-2400
Sussex County: Sussex County Prothonotary, (302) 855-7700

The Prothonotary is the county clerk responsible for recording business filings. You may file in person during business hours or by mail. Contact your county Prothonotary to confirm current procedures, as some counties may accept electronic filing.

DBA Filing Fees and Costs

Delaware does not impose a statewide DBA filing fee at the Division of Corporations level. However, county Prothonotaries charge filing fees, which vary by county and are set locally. You must contact your specific county Prothonotary to confirm the exact amount for 2026.

Additional costs may include:

Publication fees: Some counties require you to publish your DBA in a local newspaper.
Certified copies: If you need official copies of your DBA filing, the Prothonotary charges a per-page fee.
Renewal fees: When your DBA expires, you pay the county filing fee again to renew.

Contact your county Prothonotary for exact fee information, as costs vary significantly by location.

Required Contents of a Delaware DBA Filing

Delaware law does not specify a single statewide DBA form. Instead, each county Prothonotary may have its own form or accept a simple written statement. Minimum required information includes:

Your legal name (individual, LLC, or corporation name)
The assumed business name (the DBA you wish to use)
Your business address (physical location in Delaware where you conduct business)
County of filing (the county where you primarily operate)
Signature (signed by the owner, member, manager, or authorized representative)
Date of filing

For sole proprietors:

Your full legal name
Your home address or business address
The assumed business name
A statement that you are a sole proprietor

For LLCs:

The LLC's legal name (as it appears on the Certificate of Formation)
The LLC's registered agent and registered office address
The assumed business name
A statement that the LLC is filing the DBA

For corporations:

The corporation's legal name (as it appears on the Certificate of Incorporation)
The corporation's registered agent and registered office address
The assumed business name
A statement that the corporation is filing the DBA

Contact your county Prothonotary for the specific form or template they require. Many counties provide a simple one-page form that you complete and submit with payment.

How to File Your DBA: Step-by-Step Process

Step 1: Choose your DBA name. Verify that no other business in your county is using the same or confusingly similar name. While Delaware does not require a statewide name search for DBAs, you should search your county's Prothonotary records and perform a basic internet search to avoid conflicts.

Step 2: Prepare your DBA filing document. Use your county Prothonotary's form or create a simple statement containing all required information listed above. Ensure your signature is original (not photocopied or scanned).

Step 3: Submit to your county Prothonotary. Mail or deliver the completed form and filing fee to your county Prothonotary's office. Include a cover letter with your contact information and phone number.

Step 4: Receive your filing confirmation. The Prothonotary will stamp and return a copy of your DBA filing, typically within 5–10 business days. Keep this as your proof of filing.

Step 5: Publish your DBA (if required by your county). Some counties require publication in a local newspaper. The Prothonotary will inform you of this requirement and may provide a list of approved newspapers. You typically have 30 days to publish and must file an affidavit of publication with the Prothonotary.

Step 6: Update your business records. Once your DBA is filed, use the assumed name on business licenses, bank accounts, contracts, and marketing materials.

DBA Renewal and Expiration

Delaware DBAs typically expire 5 years from the date of filing. You must renew your DBA before it expires to continue using the assumed name legally.

Renewal process:

Contact your county Prothonotary 60–90 days before expiration to request renewal forms.
Complete the renewal form and submit it with the renewal fee (same as the initial filing fee).
File the renewal with the Prothonotary at least 30 days before expiration.

If your DBA expires and you do not renew, you lose the legal right to use that assumed name. Any new business using the same name can file their own DBA. If you continue operating under an expired DBA, you may face penalties or loss of legal protection.

Cancellation: If you no longer use the assumed name, you may file a cancellation with the Prothonotary to formally end the DBA registration. This is optional but recommended to avoid confusion and potential liability.

DBA vs. LLC: Which One Do You Need?

A DBA and an LLC serve different legal purposes. Understanding the distinction is critical for Delaware business owners.

A DBA is:

A fictitious name registration that allows you to operate under an assumed name.
A filing requirement for sole proprietors and a convenience for LLCs/corporations using alternate names.
Not a separate legal entity—it does not create liability protection or change your tax status.
County-level only—it provides no statewide or federal recognition.
Inexpensive and quick to file.

An LLC is:

A separate legal entity formed at the state level with the Delaware Division of Corporations.
A liability shield that protects your personal assets from business debts and lawsuits (subject to piercing the veil).
A tax-flexible structure that can be taxed as a sole proprietorship, partnership, S-corp, or C-corp.
Statewide and federally recognized for all business purposes.
More expensive ($90 filing fee + $300 annual tax) but provides substantial legal and tax benefits.

When to file only a DBA:

You are a sole proprietor operating under an assumed name.
You want minimal cost and administrative burden.
You do not need liability protection (low-risk service business, hobby business).
You are testing a business idea before committing to formal entity formation.

When to form an LLC instead:

You want personal liability protection (critical for any business with employees, inventory, or customer-facing risk).
You plan to hire employees or accept investment.
You want to establish business credit separate from personal credit.
You operate in a regulated industry (real estate, healthcare, professional services).
You anticipate growth or future sale of the business.

When to do both:

You form an LLC (for liability protection and tax flexibility) and file a DBA under the LLC's name if you operate under an assumed name. For example: "Smith Consulting LLC" (the LLC) files a DBA for "Smith Business Solutions" (the assumed name).

Publication Requirements for Delaware DBAs

Delaware does not impose a statewide publication requirement for DBAs. However, individual counties may require publication, and you must comply with your county's rules.

Contact your county Prothonotary to confirm whether publication is mandatory in your jurisdiction. If required, you must publish your DBA notice in an approved local newspaper, typically once per week for two consecutive weeks, then file an affidavit of publication with the Prothonotary.

Publication process (if required):

Contact a local newspaper approved by your Prothonotary.
Provide the newspaper with your DBA information (legal name, assumed name, address, business type).
The newspaper publishes your notice in the classified or legal notices section.
After publication, the newspaper provides you with an affidavit of publication.
File the affidavit with your county Prothonotary within 30 days of the final publication date.

Publication cost: Newspaper publication typically costs $50–$150 depending on the newspaper and number of insertions required. Check with your county Prothonotary for approved newspapers and exact costs.

DBA vs. Trademark: Protecting Your Business Name

A DBA registration is not the same as a trademark. A DBA protects your name at the county level only; a trademark protects it nationally and internationally.

DBA protection:

Valid only in the county where filed.
Prevents others in that county from registering the same DBA.
Does not prevent someone in another state or county from using a similar name.
Expires after 5 years unless renewed.

Trademark protection:

Valid nationwide (federal trademark) or internationally (Madrid Protocol).
Prevents anyone from using a confusingly similar mark in the same industry.
Lasts 10 years and can be renewed indefinitely.
Requires filing with the U.S. Patent and Trademark Office (USPTO).
Costs $250–$400 per class of goods/services.

If your business name is valuable and you plan to expand beyond Delaware, consider filing a federal trademark in addition to your DBA. This is especially important for e-commerce, online services, or branded products.

DBA for LLCs and Corporations: Special Considerations

LLCs filing a DBA:

Your LLC's Certificate of Formation includes your registered LLC name. If you operate under a different name, you must file a DBA in each county where you do business. The DBA does not change your LLC's legal name or registered agent—it simply creates a public record of the assumed name.

Example: "Delaware Tech Solutions LLC" (your registered name) files a DBA for "Tech Support Plus" (your assumed name). Contracts and legal documents should reference your LLC's legal name, but marketing and customer-facing materials can use the DBA.

Corporations filing a DBA:

Similarly, your corporation's Certificate of Incorporation establishes your legal name. If you operate under an assumed name, file a DBA in each county. Your registered agent and registered office remain unchanged.

Multi-county operations:

If your LLC or corporation operates in multiple Delaware counties, you must file a separate DBA in each county. For example, if you have offices in Wilmington (New Castle County) and Dover (Kent County), file two DBAs—one with each county Prothonotary.

Common Mistakes to Avoid

Mistake 1: Filing only a DBA when you need an LLC. A DBA provides no liability protection. If you operate a service business, retail store, or any customer-facing venture, form an LLC to shield your personal assets.

Mistake 2: Assuming a DBA is valid statewide. DBAs are county-specific. Filing in New Castle County does not protect your name in Kent or Sussex counties. If you operate statewide, file in all three counties.

Mistake 3: Neglecting to renew your DBA. If your DBA expires, you lose legal rights to the name. Set a calendar reminder 90 days before expiration to renew.

Mistake 4: Using an expired or unregistered DBA. Operating under an unregistered assumed name may result in penalties, loss of legal standing, or inability to enforce contracts. Always verify your DBA is current.

Mistake 5: Confusing DBA with trademark. A DBA does not provide trademark protection. If your business name is a brand asset, file a federal trademark with the USPTO.

Mistake 6: Not publishing when required. If your county requires publication and you skip it, your DBA filing may be invalid. Always confirm publication requirements with your Prothonotary.

Mistake 7: Filing a DBA with the state instead of the county. The Delaware Division of Corporations does not process DBA filings. You must file with your county Prothonotary, not the state.

Mistake 8: Forgetting the LLC annual tax obligation. If you form an LLC, you must pay $300 annually to the Delaware Division of Corporations by June 1, per 6 Del. C. § 18-1107(b). The DBA filing does not satisfy this requirement.

Next Steps After Filing Your DBA

Once your DBA is filed and published (if required), take these actions:

1. Obtain an Employer Identification Number (EIN). If you are a sole proprietor using a DBA, you may need an EIN for hiring employees or opening a business bank account. Apply free at https://www.irs.gov/ein.

2. Open a business bank account. Use your DBA name to open a separate bank account. Provide the bank with your DBA filing confirmation and EIN.

3. Register for Delaware business licenses. Depending on your industry, you may need a general business license, professional license, or industry-specific permit. Contact your city or county business licensing office.

4. File for state and federal taxes. Register with the Delaware Division of Revenue for sales tax (if applicable) and federal income tax. Sole proprietors report business income on Schedule C of their personal tax return.

5. Update your business records. Use your DBA name on all business documents, contracts, invoices, and marketing materials. Ensure consistency across all platforms.

6. Consider forming an LLC. If you have not already done so, evaluate whether forming an LLC would benefit your business. An LLC provides liability protection and tax flexibility that a DBA alone cannot offer.

7. Maintain your DBA registration. Set a calendar reminder to renew your DBA before it expires (typically 5 years from filing). Contact your county Prothonotary 60 days before expiration.

Contact Information for Delaware DBA Filing

Delaware Division of Corporations (for general business questions and LLC formation):

Phone: (302) 739-3073
Website: https://corp.delaware.gov/
Email: corp@delaware.gov
Address: John G. Townsend Bldg., 401 Federal Street, Suite 4, Dover, DE 19901

County Prothonotary offices (for DBA filing):

New Castle County Prothonotary: (302) 395-8000
Kent County Prothonotary: (302) 744-2400
Sussex County Prothonotary: (302) 855-7700

Contact your county Prothonotary directly for current DBA forms, filing fees, and publication requirements specific to your county.