D-U-N-S Number Guide

What is D-U-N-S Number?

A D-U-N-S Number (Data Universal Numbering System) is a unique 9-digit identifier issued by Dun & Bradstreet to a specific business location. It anchors the business credit file and is used by 230+ million businesses worldwide.

Why this matters

• Required for SAM.gov registration and most federal contracts and grants.
• Required by Apple's App Store, Google Play, and many large corporate procurement systems.
• Anchor for the D&B PAYDEX score — the most widely used business credit score.
• Free — never pay for D-U-N-S registration; D&B's upsells are optional.

How it works

• ›Submit application at dnb.com — typically 30 days free, or 5–7 business days expedited (paid).
• ›D&B verifies business name, address, phone, and federal tax ID against public records.
• ›Once issued, the D-U-N-S Number is permanent and tied to that specific business location.
• ›Trade lines and inquiries posted to your D-U-N-S build the PAYDEX file over time.

Examples in practice

Step-by-step process

1. 1

   Verify business is publicly listed

   Address, phone, and entity registration should match across state filings and listings.

2. 2

   Apply for free D-U-N-S at dnb.com

   Avoid paid expedite unless deadline-driven.

3. 3

   Activate iUpdate to manage your file

   Free portal to verify and update business data.

4. 4

   Build PAYDEX with reporting vendors

   Need at least 3 reporting trade lines for a score.

Action checklist

• Business legally formed and in good standing
• Business address verifiable (not P.O. Box for full credit applications)
• Business phone listed with directory assistance
• EIN issued
• D-U-N-S application submitted and confirmation received
• iUpdate account created

Common mistakes to avoid

• Paying for D-U-N-S — it is always free
• Applying with mismatched business data — delays verification
• Assuming D-U-N-S alone builds credit — you still need reporting trade lines

Frequently asked questions