Data Universal Numbering System (DUNS)

Definition

The Data Universal Numbering System (DUNS) number is a 9-digit identifier issued by Dun & Bradstreet for businesses worldwide. For decades, DUNS was the primary identifier used in SAM.gov registrations and federal contracting systems. In April 2022, the federal government retired DUNS in favor of the Unique Entity Identifier (UEI), a 12-character alphanumeric identifier generated and managed by SAM.gov itself. Legacy DUNS numbers may still appear on older contracts and documents, but new registrations and awards use UEI exclusively.

Why It Matters

If you work with contracts or documents dated before April 2022, you'll still encounter DUNS references. For compliance purposes, you must map your legacy DUNS to your current UEI. Some commercial databases (credit bureaus, supplier scorecards) still use DUNS, so contractors maintain both where useful. Registration pitfalls frequently arise when firms reference an outdated DUNS on a current proposal.

Example

A firm archives its DUNS (123456789) alongside its UEI (E1A2B3C4D5F6) in its SAM registration file. When submitting a CPARS rebuttal against a pre-2022 rating, it cites the DUNS under which the original award was made for clarity.

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