Answered from official registries

DBA for a sole proprietor

You work for yourself and there is no company behind you. The moment you put a name other than your own on a sign, an invoice or a bank form, most authorities want that name recorded somewhere. That record is the filing this page is about.

The counter is often local

This is the detail that sends sole proprietors to the wrong place. Of the 46 published jurisdictions with a verified authority for this filing, 19 put it in the hands of a county or local officer, against 27 that keep it central. A search result written for a company filer will point at the secretary of state, and in roughly two of every five jurisdictions that is the wrong window for you.

Jurisdictions whose verified authority for this filing is a local office:

Arkansas: County Clerk Source: www.faulknercountyar.gov official record · retrieved
Supporting excerptArkansas law requires that no person shall conduct or transact business in the state under an assumed name or under any designated name or style, corporate or otherwise, other than the real name of the individual conducting of transacting such business, unless the person files a certificate in the office of the County Clerk of the counties in which the person conducts or transacts or intends to conduct the business. The DBA certificate is filed in the County Clerk’s office and must be accomplished by: 1. In person; or 2. Mailing with the form and $25.00 Assumed Business Name Certificate
Illinois: County Clerk of the county where the business is or will be conducted or transacted Source: www.ilga.gov official record · retrieved
Supporting excerptCounty Clerk of the county where the business is or will be conducted or transacted
Indiana: County recorder of each county in which a place of business or office is situated Source: iga.in.gov official record · retrieved
Supporting excerptCounty recorder of each county in which a place of business or office is situated
Iowa: county recorder of the county in which the business is to be conducted Source: www.legis.iowa.gov official record · retrieved
Supporting excerptA person shall not engage in or conduct a business under a trade name, or an assumed name of a character other than the true surname of each person owning or having an interest in the business, unless the person first records with the county recorder of the county in which the business is to be conducted a verified statement
Kentucky: county clerk Source: apps.legislature.ky.gov official record · retrieved
Supporting excerptEach certificate of assumed name for an individual shall be filed with the county clerk where the person maintains his or her principal place of business.

Where the counter is local, the office is usually the one for the county in which you actually carry on business, and several authorities require a separate filing in each county where you operate.

How often it is mandatory

In 34 of 49 published state and District of Columbia guides, the reviewed sources state that an unincorporated owner trading under another name has to register it. Elsewhere the material reviewed either does not settle the question or treats registration as optional, and the guide says which of those it found rather than assuming the answer.

Hawaii: Indicate whether the applicant is an entity OR an individual. If the applicant is an entity, indicate whether the applicant is a corporation, a partnership, a limited liability company, a limited liability partnership, an unincorporated association, or other. Source: cca.hawaii.gov official record · retrieved
Supporting excerptIndicate whether the applicant is an entity OR an individual. If the applicant is an entity, indicate whether the applicant is a corporation, a partnership, a limited liability company, a limited liability partnership, an unincorporated association, or other.
Idaho: Sole proprietorships: If the business will be a sole proprietorship, only the business name is registered; no additional forms are needed. A sole proprietorship is owned by only one person. A sole proprietorship can be created without registering with the Idaho Secretary of State if the owner uses her/his full name (first and last name unless it is common, then include a middle initial) as a portion of the business name. Source: business.idaho.gov official record · retrieved
Supporting excerptSole proprietorships: If the business will be a sole proprietorship, only the business name is registered; no additional forms are needed. A sole proprietorship is owned by only one person. A sole proprietorship can be created without registering with the Idaho Secretary of State if the owner uses her/his full name (first and last name unless it is common, then include a middle initial) as a portion of the business name.
Illinois: No person or persons shall conduct or transact business in this State under an assumed name, or under any designation, name or style, corporate or otherwise, other than the real name or names of the individual or individuals conducting or transacting such business, unless such person or persons shall file in the office of the County Clerk of the County in which such person or persons conduct or transact or intend to conduct or transact such business, a certificate setting forth the name under which the business is, or is to be, conducted or transacted, and the true or real full name or names of the person or persons owning, conducting or transacting the same. Source: www.ilga.gov official record · retrieved
Supporting excerptNo person or persons shall conduct or transact business in this State under an assumed name, or under any designation, name or style, corporate or otherwise, other than the real name or names of the individual or individuals conducting or transacting such business, unless such person or persons shall file in the office of the County Clerk of the County in which such person or persons conduct or transact or intend to conduct or transact such business, a certificate setting forth the name under which the business is, or is to be, conducted or transacted, and the true or real full name or names of the person or persons owning, conducting or transacting the same.

What it costs

Local filing tends to mean smaller, more varied charges than central registration, and several counties price by the number of owners named on the certificate. Fees appear here exactly as the authority publishes them.

Colorado: $20.00 Source: www.coloradosos.gov official record · retrieved
Supporting excerptTrade namesOnline feePaper feeTrade Name Statement$20.00n/aTrade Name Renewal$5.00n/aTrade Name Withdrawal$10.00n/aChange of Trade Name Information$10.00n/aCorrection of Trade Name Information$10.00n/a
Connecticut: $20 filing fee Source: business.ct.gov official record · retrieved
Supporting excerpt$20 filing fee A trade name is filed with the local town clerk where the business is primarily transacted. When you deliver the trade name application to the town clerk, you must pay a $20 filing fee payable to the town clerk.
Delaware: The fee is a one-time $25 charge per trade name. Source: onestop.delaware.gov official record · retrieved
Supporting excerptThe fee is a one-time $25 charge per trade name.
District of Columbia: $55.00 Source: dlcp.dc.gov official record · retrieved
Supporting excerptTrade name registration application: $55.00
Florida: $50 Source: www.flsenate.gov official record · retrieved
Supporting excerpt(12) PROCESSING FEES.—The division shall charge and collect nonrefundable processing fees as follows: (a) For registration of a fictitious name, $50. (b) For cancellation or cancellation and reregistration of a fictitious name, $50. (c) For renewal of a fictitious name registration, $50. (d) For furnishing a certified copy of a fictitious name registration document, $30. (e) For furnishing a certificate of status, $10.

What the filing is not

Be clear about what the certificate buys, because its effect is modest. Recording a name does not create a company, and it is not the local business licence your city may demand separately. Nor does it settle who owns the words: an authority that accepts your certificate is not promising to turn anyone else away. One registry states all of that outright, and that passage is quoted on the comparison page.

Whether to form a company instead, or as well, is a decision for a qualified adviser. This site documents the name filing only.

Read the rule for your state

Start with your jurisdiction's guide for the office, the official term, the fee, the duration and the renewal position. Where a county holds the filing, published county guides go further and give that office's own form and counter details.

Frequently read: Texas and its Harris County guide, California with Los Angeles County, and New York. Or use the finder.