A Contract Line Item Number (CLIN) is the four-digit building block the federal government uses to organize, price, and pay for everything in a contract. If you sell to federal agencies—or plan to—understanding CLINs is essential, because they define exactly what you are delivering and how you get paid. This guide explains what a CLIN is, how it is formatted, how it differs from SLINs, and why it matters on a GSA Schedule.
What is a contract line item number (CLIN)?
A Contract Line Item Number (CLIN) is a numbered entry in a federal contract that identifies a single deliverable—a product, service, or task—along with its quantity, unit price, and delivery terms. Every priced thing in a federal contract sits on its own CLIN so the government can track and pay for it separately. CLINs are governed by the Uniform Contract Format under the Federal Acquisition Regulation (FAR).
What does a CLIN look like?
A CLIN is a four-digit number, starting at 0001 and increasing sequentially (0002, 0003, and so on). A simple supply contract might show:
| CLIN | Description | Qty | Unit Price |
|---|---|---|---|
| 0001 | Laptop computers, ruggedized | 50 | $1,800 |
| 0002 | On-site installation & setup | 1 | $4,500 |
| 0003 | 3-year extended warranty | 50 | $220 |
CLINs vs. SLINs vs. ELINs
When a single line item needs to be broken into smaller pieces—for example, the same product funded by two different appropriations—the government uses a Subline Item Number (SLIN). SLINs add two more characters to the CLIN (e.g., 0001AA, 0001AB). An Exhibit Line Item Number (ELIN) references deliverables documented on a separate exhibit. In short: the CLIN is the parent; SLINs and ELINs are its children.
Why CLINs matter on a GSA Schedule
On a GSA Multiple Award Schedule (MAS) contract, your awarded products and services are organized into line items tied to Special Item Numbers (SINs). When an agency places an order, those items become CLINs on the resulting task or delivery order. Clean, well-structured line items make your quotes and invoices easier for contracting officers to approve—and easier for you to get paid.
How CLINs affect getting paid
Invoices must map line-for-line to the CLIN structure in the order. If your invoice does not match the CLINs and quantities exactly, payment can be rejected or delayed. This is also why CLINs matter during contract administration and any contract extension or modification—changes are made at the line-item level.
Frequently asked questions
How many digits is a CLIN?
A CLIN is four digits (e.g., 0001). Sublines (SLINs) append two additional characters, such as 0001AA.
What is the difference between a CLIN and a SLIN?
A CLIN is the main contract line item. A SLIN subdivides a CLIN into smaller parts—often to separate funding sources or delivery details—without changing the parent line item’s scope.
Who assigns CLINs?
The contracting officer establishes the CLIN structure in the solicitation and resulting contract, following the FAR Uniform Contract Format.
New to federal contract structure? Book a free discovery call with a GSA expert and we will walk you through it. — Reviewed by the GSA Focus team.
