GSA Schedule basics: "commercial," "fixed price," and how to sell more with Add SIN
Two rules shape everything you sell on a GSA Schedule: it must be commercial, and your prices are fixed. What that means, and how Add SIN helps you sell more.
The short answer: Everything you sell through your GSA Schedule must be something you also sell in the commercial market, and your contract prices stay fixed unless you adjust them the way your contract allows. If your business has grown into new areas, you don't need a new contract to sell them to the government. You can add a new category, called a SIN, to the contract you already have.
Rule 1: it has to be commercial
GSA Schedules are for commercial products and services: things businesses or the public buy too, at normal market prices.
A quick test: do other customers buy this from you, or from companies like yours? If yes, it's likely commercial.
Be ready to show it: GSA may ask for proof, such as invoices or a price list.
Rule 2: your prices are fixed
Your GSA prices are set in your contract. They don't change from order to order.
To raise prices, you follow the price adjustment terms in your contract.
Agencies can still order in different ways, such as a fixed total price for a project or by the hour. Your contract rates are the ceiling either way.
Grow your contract with Add SIN
Your business grows, but your GSA contract only grows if you ask. A SIN (Special Item Number) is a category of what you sell. Adding one lets agencies buy more from you through the contract you already have.
A consulting firm that also runs training can add a training SIN, so agencies can buy both from one contract.
An IT firm can add a category for work it already does for commercial clients.
A product seller can add a category for a new product line.
Two things make an Add SIN request go smoothly:
Proof it's commercial: invoices or a price list for the new work.
Relevant experience: a recent project or two that shows you already do this work.
Where to start
List what you sell today that your GSA contract doesn't cover.
Find the GSA category (SIN) that fits.
Gather invoices or a price list, and a recent project or two.
Preparing an Add SIN request, step by step, is one of the jobs AcqVerity is built for. We're opening a small early-access group; join the list at AcqVerity.com.
This guide is general information from public sources, including GSA's MAS Modification Guide, as of October 2026. It is not legal or contracting advice. Your contract terms, GSA and your Contracting Officer decide. AcqVerity Technologies LLC is not affiliated with GSA.