How to Fill Out Navajo Nation Form 100: Designation of Individual

To fill out Navajo Nation Form 100, enter your business’s identifying information at the top, name one individual as your designee in Section 1, check a single Navajo tax type in Section 3, complete the business-type and accounting sections that follow, sign and date the form, and mail it to the Office of the Navajo Tax Commission (ONTC) in Window Rock, Arizona. The form fits on one page, but you file a separate copy for each tax type that applies to your business.¹

Before You Start

Download the current version from the ONTC website. The 2026 form carries revision date September 25, 2025.¹ Have three things in front of you:

Your employer identification number from the IRS. If you don’t have one, a Social Security number works, or you can apply for an EIN using IRS Form SS-4.²
A decision about which Navajo tax or taxes apply to your activity. You can only check one box per form, so if more than one tax applies, you’ll fill out and submit a separate Form 100 for each.³
The street address where your accounting records are physically kept. A P.O. box is not accepted for this field.³

The Top of the Form

Three fields sit above the numbered sections.

EIN/SSN. Enter the IRS-assigned EIN for the business, or your Social Security number if you operate without one.³

Business Name. Write the legal name the business operates under.

Nature of Business. Describe what the business actually does. Retail sales, construction, fuel distribution, and lodging are examples of the level of detail expected.

Section 1: Designee Information

The designee is the single person who will receive every tax notice and piece of correspondence the ONTC sends about this business. It has to be a real individual, not a company name.³ Who you can name depends on how the business is organized: a sole proprietor can name themselves, a partnership can name any individual partner, and a corporation can name any officer or employee.⁴

Fill in the designee’s full name, title, mailing address, city, state, zip code, phone number, and email address.

Section 2: Navajo Nation Physical Address

If the business has a physical location within the Navajo Nation that differs from the designee’s mailing address, enter that address and phone number here. If there is no separate Navajo Nation address, write “N/A.”¹

Section 3: Tax Type

Check one box, and only one. The 2026 form uses these abbreviations:

SALES — Sales Tax
BAT — Business Activity Tax
HOT — Hotel Occupancy Tax
FET — Fuel Excise Tax
SEV — Oil and Gas Severance Tax
TOB — Tobacco Products Tax
ALT — Alcohol Tax
LIQ — Liquor Tax
JFT — Junk Food Tax
E-SMOKE/NIC — E-cigarette and Nicotine Products Tax

Most retail operations check SALES. A restaurant that also serves alcohol would file one Form 100 for SALES and a second for LIQ. A construction contractor doing project work on Navajo land may register only for BAT. Think through each revenue stream and submit one Form 100 per applicable tax.

Sections 4 Through 7

Section 4 — Type of Business. Check one: Corporation, Partnership, Joint Venture, Sole Proprietorship, or Other. If you check Other, specify in the space provided.¹

Section 5 — Accounting Year End. List the month your fiscal year closes. For most businesses on a calendar year, that is December.

Section 6 — Accounting Method. Check Cash or Accrual.

Section 7 — Records Location. Give the street address, city, and state where your accounting records are kept. Not a P.O. box.³

Signature

The designee, an officer, or another authorized representative must sign and date the form. An unsigned Form 100 is invalid, and the ONTC will mail it back for a signature.³ Check it before you seal the envelope. This is the single most common reason a filing bounces.

Where To Send It

Mail completed forms to:

Registrar, Office of the Navajo Tax Commission
P.O. Box 1903
Window Rock, Arizona 86515-1903³

The ONTC’s instructions do not list a filing fee for Form 100 itself. It is a registration document, not a permit application.

When To File

Three deadlines control Form 100:

First-time filers. The form must be on file before you submit your first tax return under any Navajo tax law.³
Annual refile. File a fresh Form 100 by January 15 each year, even if nothing has changed.
Mid-year changes. File a revised Form 100 within 30 days of any change in designee, address, ownership, or other circumstances affecting the registration.

The January 15 deadline is easy to miss because nothing else triggers it. No invoice arrives, no reminder is sent. Put it on a recurring calendar now.

Don’t Confuse Form 100 With BRD Registration

Form 100 registers you for Navajo tax purposes with the ONTC. It is separate from the business authorization process run by the Business Regulatory Department (BRD) under the Division of Economic Development, which handles corporate registration, Navajo Business Opportunity Act certification, and Certificates of Authority for foreign corporations. The BRD instructs filers directly: “DO NOT send the FORM-100 or any other tax documents to the BRD.”⁵ Keep the two filings in separate envelopes going to separate offices.

1
Navajo Nation Office of the Navajo Tax Commission. Navajo Nation Form 100
2
Internal Revenue Service. About Form SS-4, Application for Employer Identification Number (EIN)
3
Navajo Nation Office of the Navajo Tax Commission. Instructions for Form 100
4
Navajo Nation Office of the Navajo Tax Commission. Instructions for Form 100
5
Navajo Nation Division of Economic Development. NBOA Registration and Certification