UEI Numbers Explained — The DUNS Replacement Every Contractor Needs

By Sean & Doug Reitmeyer — GCExperts. Written from real contractor conversations, calls, and workshops.

For decades, if you wanted federal work, you needed a DUNS number from a company called Dun & Bradstreet. Then the government finally did what everyone wanted: it made the identifier free and self-service. The DUNS number is gone. The UEI is here. And if you're new to federal contracting, this is one of the first things you'll run into.

UEI stands for Unique Entity Identifier. It's a twelve-character code that identifies your business to the federal government — one code, one entity, forever. Unlike the old DUNS system, where you registered with a private company and paid fees for extras, the UEI is issued by SAM.gov itself, free, when you register your entity. No middleman. No annual fee. Just your business, its legal name, and its tax ID.

Where do you find yours? If you've registered in SAM.gov at any point in the last few years, you already have one. Log into your SAM account and it's right there on your entity record. If you're registering for the first time, the system generates it during registration. And if you're a subcontractor who's never registered because the prime contractor handles everything, here's the part that matters: primes increasingly need your UEI to onboard you, and the government needs it on every award, every invoice, every report that touches your company.

A few things to keep straight. Your UEI belongs to your legal entity, so if your company's legal structure or name changes, check whether the identifier needs to follow the change — the system handles most of that when you update your registration, but you want it right before award time, not discovered during award time. Your UEI is different from your NAICS codes, which describe what you do, and different from your cage code, which is a separate identifier used mainly for government logistics and payment systems. And yes, the government's systems are full of old forms that still say DUNS — if a form asks for your DUNS, give them your UEI; that's the replacement, and the people on the other end know it.

The short version: the UEI is your company's federal fingerprint. It's free, it's permanent, and it should be on the first page of your records — because it'll be on the first page of every contract you sign.