Quick answer: A CLIN, or contract line item number, is the numbered line on a government contract or quote that identifies one deliverable: a product, a service, a block of labor or a data item. Each line item carries its own price, quantity and delivery terms, which is how the government orders, accepts, pays for and funds what it buys. If you sell through a contract vehicle like NASA SEWP, your CLINs are also your catalog: what isn't on contract as a CLIN usually can't be quoted.
This question came up live on a SEWP webinar last month, when a contract holder asked the room what tools people use to manage "the CLINs process." With SEWP VI now open for orders, a lot of teams are building CLIN catalogs for the first time. This post covers the basics that apply to any federal contract, then how CLINs work on a product vehicle. For the step-by-step mechanics of adding CLINs on SEWP, see our guide to the SEWP VI Technology Refresh (TR) process.
What does a CLIN mean in a federal contract?
The Federal Acquisition Regulation (FAR) doesn't actually use the acronym. It talks about "line items" and "contract line item numbers." FAR 4.1001 says line items "are established to define deliverables or organize information about deliverables."
In a solicitation, CLINs usually appear in the schedule of supplies or services, often Section B of an RFP that follows the uniform contract format. The government lists what it wants line by line, and offerors price each line. When the contract is awarded, those same lines become the basis for orders, invoices and payment. (If you need a refresher on the solicitation types themselves, see RFI vs. RFQ vs. RFP.)
When does something need its own CLIN?
Under FAR subpart 4.10, a deliverable gets a separate line item when it differs from other deliverables in any of these ways:
- It needs to be separately identified
- It has its own unit price or total price
- It's charged to a single, different accounting classification (a different pot of funding)
- It has its own delivery schedule, destination or period of performance
- It uses a different pricing type, such as firm-fixed-price versus time-and-materials
That's why a single hardware buy can turn into a dozen CLINs: the servers, the installation labor, the three years of support and the training might each have different prices, funding or delivery dates. And under FAR 4.1006, adding a new item to an existing contract means adding a new line item number rather than reusing an old one.
What are SLINs, and what's the difference between priced and informational lines?
A subline item (SLIN) sits under a CLIN. The FAR allows two kinds:
- Deliverable sublines are real, separately deliverable items, each with its own quantity and price.
- Informational sublines exist only to organize administrative detail. FAR 4.1004 says to put them "within the line item description, not in the quantity or price fields."
One rule trips people up: if a line item has deliverable sublines, the parent line item becomes informational (FAR 4.1001(b)). In that case you price the sublines, not the parent.
How are CLINs numbered?
The FAR leaves numbering to "agency procedures." The most widely copied format comes from the Department of Defense, in DFARS PGI 204.71:
- CLINs are four numeric digits, 0001 through 9999.
- Informational sublines add two digits, 01 through 99 (for example, 000101).
- Separately identified sublines add two letters, AA through ZZ (for example, 0001AA). The letters I and O aren't used, so they can't be confused with 1 and 0.
Whatever the format, check the solicitation: the numbering the buyer uses in its schedule is the one your quote or proposal has to match.
How do CLINs work on a contract vehicle like SEWP?
On a one-off contract, the government writes the CLINs. On a product vehicle like NASA SEWP, the contract holder builds them. Your CLINs become the approved catalog that agencies can order from, and you add or change them through a Technology Refresh.
That changes what "managing CLINs" means. A few rules from the SEWP VI Contract Holder User Manual (August 21, 2026) show the scale of it:
- One configuration, one CLIN. The manual says holders "CANNOT have a CLIN on contract that you reuse for different configurations, pricing strategies, support options, etc."
- Labor comes first. "Labor rates must be added to the contract first," and any labor CLIN covering more than a day has to be a bundle.
- Retired means retired. "Once you EOL a CLIN, that CLIN cannot be reused." Plan your naming so you aren't stuck when a product comes back in a new version.
- No free lines. Holders can't quote a CLIN at $0 if its contract price is above $0.
Timing matters too. According to the SEWP Program Office, SEWP V and SEWP VI run side by side from November 1, 2026 to January 31, 2027, and SEWP recommends agencies use SEWP VI unless they have a specific reason not to. Holders who carry both contracts are maintaining two catalogs at once until SEWP V stops taking new orders.
CLINs also aren't the same thing as product classification codes, which describe what an item is rather than how it's priced on a contract; see what a UNSPSC code is.
How should a team manage CLINs day to day?
- Name one owner. Someone has to decide when a quote needs a new CLIN and keep the catalog clean.
- Map configurations before you build lines. Every hardware configuration, support term and license tier you plan to quote should map to its own line.
- Connect pricing changes to the catalog. When an OEM or distributor changes a part number or price, the CLIN usually has to change too.
- Match the buyer's structure on one-off bids. When the government writes the CLINs, price exactly what's listed. Don't merge or split lines unless the solicitation allows it.
Where Govly fits
Govly brings RFQs from vehicle ordering portals, including NASA SEWP, GSA eBuy and Army CHESS, into one feed alongside SAM.gov, so your team can see what buyers are asking for before deciding which CLINs to build. For SEWP VI holders, Govly tailors the opportunity feed to your category and catalog and templatizes TR files, so adding CLINs becomes a repeatable process. If you're also tracking other vehicles, here's why contract vehicle RFQs don't appear on SAM.gov.
Building your CLIN catalog for SEWP VI? Book a demo.
FAQ
Is a CLIN the same as a GSA SIN?
No. A SIN (special item number) is a category on the GSA Multiple Award Schedule that groups similar offerings, while a CLIN identifies one specific priced deliverable.
What is an ELIN?
An exhibit line item number identifies a deliverable listed in an exhibit attached to a DoD contract rather than in the main schedule. Under DFARS PGI 204.7105, it uses a four-position number that starts with the exhibit's letter identifier.
What are "Z" CLINs on SEWP?
They're variably priced CLINs for things like travel, delivery, credits and other direct costs. The SEWP VI manual says a quote using one must state the dollar amount and describe its specific use.
