How to Get a Tax ID Number in Kentucky: EIN and Tax Account

To get a tax ID number in Kentucky, you actually need two of them: a federal Employer Identification Number (EIN) from the IRS, and a Kentucky Tax Account Number from the state Department of Revenue. The EIN is free and issued in minutes online. The state account is handled through Kentucky’s MyTaxes portal once your business legally exists. Order matters — the Department of Revenue lays out a specific three-step sequence, and jumping ahead slows everything down.¹

Step 1: Legally Form Your Business

You can’t register for tax accounts until your business legally exists. Where you file depends on structure.

Sole proprietorships and general partnerships register with the county clerk in the county where the business operates. LLCs, corporations, and limited partnerships file formation documents with the Kentucky Secretary of State.¹ The Secretary of State charges $40 to file articles of organization for an LLC or articles of incorporation for a for-profit corporation. Nonprofit corporations pay $8.²

Step 2: Apply for Your Federal EIN

Once your entity exists, apply for a federal EIN. This nine-digit number works like a Social Security Number for your business. The IRS uses it to track your filings, and you’ll need it to open a business bank account, hire employees, and file federal returns.³

You need an EIN if your business is a corporation, partnership, or multi-member LLC. Sole proprietors and single-member LLCs need one once they hire employees. Any business that files excise taxes, or withholds taxes on non-wage income paid to a nonresident alien, also needs one.³

Apply Online

The IRS online application is free, and you receive your number immediately when you finish.⁴ The tool is open Monday through Friday from 6:00 a.m. to 1:00 a.m. Eastern, Saturdays from 6:00 a.m. to 9:00 p.m., and Sundays from 6:00 p.m. to midnight.⁵

Two practical points. The application cannot be saved and times out after 15 minutes of inactivity, so complete it in one sitting. The IRS also limits you to one EIN application per responsible party per day.⁵ To use the online tool, your principal place of business must be in the United States or a U.S. territory, and you’ll need the responsible party’s Social Security Number or Individual Taxpayer Identification Number.

One warning. The IRS charges nothing for an EIN. Third-party sites sometimes charge a fee to submit the same application for you. If a site asks for payment, you’re not on the IRS website.

Apply by Fax or Mail

If you can’t use the online tool, submit IRS Form SS-4 by fax or mail. Faxed applications are processed under the Fax-TIN program and typically return your EIN within four business days. Mailed applications take roughly four to five weeks.⁶ For businesses in any of the 50 states or Washington, D.C., fax Form SS-4 to 855-641-6935 or mail it to the IRS EIN Operation in Cincinnati, OH 45999.⁷

Step 3: Register for a Kentucky Tax Account Number

With your entity formed and your EIN issued, register with the Kentucky Department of Revenue. The state assigns a nine-digit account ID that you’ll use for all state tax filings.⁸

You’ll need a Kentucky Tax Account Number if your business does any of the following:

Sells taxable goods or services to Kentucky customers (sales and use tax).
Pays employees and withholds Kentucky income tax from wages.
Operates in an industry with separate registration requirements, such as utilities, telecommunications, or tobacco and vapor products.

Register Online Through MyTaxes

The fastest route is the MyTaxes portal at mytaxes.ky.gov. This system replaced Kentucky’s older E-Tax and OneStop platforms and now handles registration for sales and use tax, corporate income tax, withholding, and other account types.⁸ You can register for multiple tax accounts in the same session.¹

Register on Paper

If your business structure isn’t available in the online system, submit Form 10A100, the Kentucky Tax Registration Application, by mail, fax, or email.⁹ Paper applications can take up to three weeks to process.¹ Mail the completed form to the Kentucky Department of Revenue, Division of Registration, 501 High Street, Station 20, Frankfort, KY 40602-0299. You can also fax it to 502-227-0772 or email it to DOR.Registration@ky.gov.

What to Have Ready Before You Apply

Gathering the following information before you start will keep you from timing out mid-application:

Your entity’s exact legal name as it appears on formation documents, or your full legal name if you’re a sole proprietor.
Entity type — sole proprietorship, partnership, LLC, corporation, or nonprofit.
Physical business address and a mailing address for correspondence.
The date you began or plan to begin operations.
A description of your principal business activity.
The responsible party’s name and SSN or ITIN, for the federal EIN application.

The responsible party requirement trips people up more than any other item on the EIN application. The IRS defines this as someone who owns, controls, or exercises effective control over the entity and directly or indirectly manages its funds and assets. For corporations, that’s usually the principal officer. For partnerships, it’s a general partner. For trusts, it’s the grantor or trustor.¹⁰ The responsible party must be an individual person, not another business entity. Nominees with only limited formation authority don’t qualify.

When You’ll Need a New EIN Later

Your EIN doesn’t automatically follow you through every business change. Certain structural shifts require a brand new number rather than an update to the existing one. The IRS sets the triggers by entity type:¹¹

Sole proprietors need a new EIN if they incorporate, form a partnership, or declare bankruptcy.
Corporations need a new EIN if they receive a new charter from the secretary of state, convert to a partnership or sole proprietorship, or create a new corporation through a merger.
Partnerships need a new EIN if they incorporate, dissolve and start a new partnership, or if one partner takes over as a sole proprietor.
LLCs need a new EIN if the existing LLC is terminated and reformed as a new corporation or partnership.

Simpler changes, like a new business address or a change of responsible party, don’t require a new EIN. Those are reported on IRS Form 8822-B.¹²

Penalties for Not Registering

Skipping registration carries real financial cost. Failing to obtain a required tax identification number, permit, or license in Kentucky triggers a penalty of 10% of any associated cost or fee, with a $50 minimum.¹³

Once you’re behind, the penalties compound. Late-filed returns trigger a 2% penalty on the total tax due for each 30-day period the return is overdue, up to a 20% maximum. Late payments carry the same 2% per 30-day structure. Kentucky also charges 9% annual interest on unpaid tax balances for 2026, and that interest is set by statute and cannot be waived.¹³

The IRS doesn’t impose a standalone penalty for not having an EIN. But without one you can’t properly file federal returns, and the cascading late-filing penalties that follow almost always cost more than the few minutes it takes to apply in the first place.

1
Department of Revenue. Business Registration
2
Kentucky Secretary of State. Fees
3
Cornell Law School Legal Information Institute. Employer Identification Number (EIN)
4
Internal Revenue Service. Employer Identification Number
5
Internal Revenue Service. Get an Employer Identification Number
6
Internal Revenue Service. Instructions for Form SS-4
7
Internal Revenue Service. Where to File Your Taxes for Form SS-4
8
Kentucky Department of Revenue. MyTaxes
9
Kentucky Department of Revenue. 10A100 Kentucky Tax Registration Application and Instructions
10
Internal Revenue Service. Responsible Parties and Nominees
11
Internal Revenue Service. When to Get a New EIN
12
Internal Revenue Service. Form 8822-B Change of Address or Responsible Party – Business
13
Kentucky Department of Revenue. Penalties, Interest and Fees