UEI vs. CAGE Code vs. DUNS Number: What's the Difference?

What Is a UEI, and How Is It Different From a CAGE Code and a DUNS Number?

Your Unique Entity ID (UEI) is the 12-character identifier that SAM.gov assigns to your business the moment you register — it's your primary ID across every federal system. Your CAGE code is a separate 5-character code assigned by the Defense Logistics Agency (DLA) during that same SAM registration, used mostly for logistics, contracting, and supply chain tracking. The DUNS number was the old identifier both of these replaced — Dun & Bradstreet stopped being the government's ID system in April 2022, and DUNS numbers are no longer used anywhere in federal contracting or grants.

If you're filling out an SF-424, an SF-1449, or trying to figure out why a contracting officer is asking for a "CAGE" when you just gave them a "UEI," this confusion is extremely common. Let's sort it out identifier by identifier.

The Unique Entity ID (UEI)

The UEI is a 12-character alphanumeric code (no letters I, O, S, or the numeral 0 or 1 — the algorithm avoids visually ambiguous characters) generated automatically by SAM.gov when you complete your entity registration. You don't apply for it separately, and you can't request one from a third party. It's free, and it's tied permanently to your business's legal entity registration in SAM.

Where you'll see the UEI used:

• SAM.gov entity registration and renewal
• Grants.gov applications, including the SF-424 family of forms
• Federal contract award documents and FPDS (the government's contract reporting database)
• Subcontracting plans and small business subcontracting reports
• Most agency-specific portals that pull entity data from SAM (e.g., PIEE, FPDS-NG, FSRS)

Think of the UEI as your business's federal "fingerprint." Everything — contracts, grants, past performance, your SBA certifications — rolls up to that one number.

The CAGE Code

A CAGE code (Commercial and Government Entity code) is a 5-character ID assigned by DLA's CAGE program specifically for U.S. and Canadian entities doing business with the federal government. If you register in SAM.gov as a U.S. entity, DLA automatically assigns you a CAGE code as part of that registration — you don't do anything extra to get one, but it's a distinct number from your UEI, issued by a different agency for a different purpose.

CAGE codes predate the UEI system by decades and originated in defense logistics and supply contracting, which is why you'll see them most on:

• SF-1449 (Solicitation/Contract/Order for Commercial Items)
• DoD contract documents, DFARS clauses, and invoicing systems like WAWF/iRAPT (now part of PIEE)
• Supplier and vendor master files at prime contractors
• Quality and inspection records tied to specific manufacturing or supply locations

One wrinkle worth knowing: large companies with multiple facilities can hold several CAGE codes under one UEI — one per physical location. Small businesses usually have just one CAGE code tied to their single UEI, but don't be surprised if a prime contractor or agency asks specifically for the CAGE code on a facility-level form even though you've already given them your UEI elsewhere.

You can look up any entity's CAGE code for free through SAM.gov's entity search or DLA's CAGE search tool — no account needed, and it's useful for verifying a subcontractor or teaming partner before you sign anything.

The DUNS Number (Retired — But You'll Still See References to It)

Until April 2022, the federal government used Dun & Bradstreet's proprietary DUNS number as the primary entity identifier in SAM.gov, right alongside the CAGE code. The government moved away from DUNS for two practical reasons: it was controlled by a private company (creating cost and dependency issues), and it didn't integrate cleanly with other federal data systems the way a government-owned identifier could.

If you registered in SAM before 2022, your DUNS number was automatically mapped to a newly generated UEI — you didn't lose any history, and your past performance record carried over. But here's where people still get tripped up:

• Old templates, outdated agency guidance PDFs, and even some state-level or prime contractor forms still say "DUNS number." If you see that today, just provide your UEI instead — DUNS numbers can no longer be verified or issued.
• Some legacy proposal boilerplate (especially recycled grant templates) still has a "DUNS" field. Don't leave it blank; swap in your UEI and move on.

If a form absolutely insists on a DUNS number and gives you no way around it, that's a sign the form itself hasn't been updated — flag it to the program office rather than trying to track down a defunct number.

EIN/TIN: The Fourth Identifier Nobody Mentions

The brief here is about UEI, CAGE, and DUNS, but it's worth a quick note on the one other number every federal form touches: your EIN (Employer Identification Number), also called a TIN for tax purposes. This is issued by the IRS, not SAM.gov or DLA, and it's used for tax reporting, banking, and as part of your SAM registration validation (SAM now verifies your legal business name and EIN directly with the IRS during registration). You'll enter your EIN on W-9s, SF-424 budget forms, and electronic funds transfer (EFT) setup — but it's a tax ID, not a contracting or logistics ID, so don't confuse it with your UEI or CAGE code even though all four numbers often sit on the same form.

Where Each Identifier Shows Up: Quick Reference

Getting This Right the First Time

Mixing up these identifiers doesn't just cause paperwork headaches — a mismatched or missing UEI/CAGE on a proposal is one of the more common reasons small businesses get bounced on compliance before an evaluator even reads their technical approach. If you're assembling your first few proposals and want someone to double-check that every identifier, certification, and attachment lines up before submission, it's worth having a second set of eyes — whether that's a capture consultant or a platform built to catch it automatically (book a 15-minute walkthrough) rather than finding out after a rejection notice.

Keeping your UEI, CAGE code, and EIN straight — and knowing which form wants which one — is a small thing, but it's exactly the kind of small thing that separates businesses that submit clean, compliant proposals from ones that get kicked back in the first compliance screen. If you're weighing whether to handle registration and compliance checks in-house versus using a tool that keeps all of this synced automatically, it's worth comparing the real cost either way (see what InstaGovOps costs vs hiring this in-house) before you commit a hire or a contract to it.