Winvale Blog

GSA Resources 101: 7 Sites Every MAS Contractor Should Know

Written by Emma Pasqualino | Sep 12, 2025 2:24:13 PM

GSA Schedule acquisition isn’t a simple process, but fortunately, GSA has developed resources to help make it more manageable. Whether you're a seasoned GSA contractor working to maintain your contract or a prospective contractor pursuing your first one, the resources listed below will be valuable to your company throughout both the acquisition and maintenance phases.

The System for Award Management (SAM.gov)

The System for Award Management (SAM.gov) is one of the most important resources for GSA contractors. Contractors use SAM.gov to access contracting opportunities, wage determinations, entity information, and reporting. Most importantly, registration with SAM.gov is required for companies to obtain a GSA Schedule and sell to the government. Through SAM.gov, your company receives its Unique Entity Identifier (UEI), which is essential for acquiring a GSA Schedule. Your UEI is permanent and stays with your company.

To register for a UEI, you’ll need documentation to verify your entity information, such as articles of incorporation or proof of a government-issued tax identification number. It’s imperative that all your company’s information is accurate, and that SAM.gov is updated promptly if any changes occur. You also must renew your SAM.gov registration annually to keep your record compliant.

Vendor Support Center

The Vendor Support Center (VSC) is a highly valuable site, providing access to all the resources and tools you’ll need as a GSA contractor. From here, you can access the FAS Sales Reporting Portal, the Mass Mod System, eOffer/eMod, GSA Advantage, GSA eBuy, eLibrary, and more. The Vendor Support Center also keeps you up to date with GSA events and training programs.

Once your contract is awarded, it must be registered with the Vendor Support Center in order to participate in tools like GSA Advantage and eBuy. Any questions you may have about obtaining or managing a contract can be answered through this site, making it one of the most important websites to become familiar with.

GSA Advantage

GSA Advantage! is like Amazon for the government. This site provides government agencies with access to contractors and their products and services in just a few clicks. After registering through the Vendor Support Center, contractors can begin receiving orders from federal, state, and local agencies via GSA Advantage!. As a contractor, you’ll also be able to market your products and services directly through the platform. Participating in GSA Advantage! is a great way to increase visibility for your company’s offerings and expand your reach within the public sector.

GSA eBuy

GSA eBuy is a one-stop shop for contractors to increase sales potential and discover new opportunities. It’s a Request for Quote (RFQ) tool used by government agencies to request quotes from contractors for commercial products and services. Government buyers also release Requests for Information (RFIs) and Requests for Proposals (RFPs) on this site. GSA eBuy is only available to companies with a GSA Schedule and helps contractors achieve required competition, best pricing, and best value. You only see opportunities related to your Special Item Numbers (SINs) on GSA eBuy, which helps you narrow down and streamline your search. We suggest contractors monitor this site daily for relevant opportunities, especially during Q4 of the federal fiscal year (July 1 – September 30).

Mass Modification System

After being awarded a GSA Multiple Award Schedule contract, your contract will require modifications over its lifetime to remain current and compliant. GSA routinely issues Mass Modifications through the Mass Modification System, often in connection with solicitation refreshes. Mass Modifications are different from contract modifications because they are GSA-initiated. These mass modifications and associated Solicitation Refreshes outline significant changes that could impact your contract, and you must submit your acceptance within 90 days of the modification being released. The latest Mass Modification was released late last month for Solicitation Refresh #29.

At Winvale, we make it a priority to stay on top of Mass Modifications and provide detailed summaries of the significant changes being made, so you can better understand the modification you’re signing.

GSA eOffer/ GSA eMod

GSA eOffer and GSA eMod are essential tools for both prospective and current MAS contractors. Through these platforms, contractors can prepare and submit their Multiple Award Schedule offers, submit modification requests, and access the FAS Sales Reporting Portal to report sales, depending on the method used.

GSA eOffer allows prospective contractors to prepare and submit a Multiple Award Schedule offer. Before submitting an offer, we recommend reviewing our guide “How Do I Get a GSA Schedule Contract?”

GSA eMod enables MAS contractors to prepare and submit contract modification requests, including additions, administrative changes, deletions, and more. To learn more about the types of requests that can be submitted through eMod, check out our blog “What Are the Types of GSA Schedule Contract Modifications?”

The FAS Sales Reporting Portal is used by contractors to track sales and pricing using one of two methods:  Commercial Sales Practices (CSP) or Transactional Data Reporting (TDR). You can also access this portal at srp.fas.gsa.gov/. As a contractor, submitting your sales and pricing data is required to remain in compliance with your contract. It’s anticipated that GSA will make TDR mandatory for all Special Item Numbers (SINs) in the future. For more information on TDR and reporting requirements, visit our blog, “Transactional Data Reporting (TDR) for Beginners.”

GSA eLibrary

GSA eLibrary houses the latest GSA contract award information and offers a wide range of acquisition services. Most importantly, it contains the most up-to-date contract details and serves as a valuable research tool for anyone interested in acquiring a GSA Schedule. GSA eLibrary also allows you to research your competitors to gain insight into the products and/or services they offer and at what price. Additionally, it provides compliance-related information such as contract renewal dates, expiration dates, and government points of contact (POCs).

Thinking About Getting a GSA MAS Schedule Contract?

While there are plenty of additional resources contractors can use throughout the life of a GSA Schedule contract, the ones listed above are especially useful and will be part of your daily routine, especially when it comes to contract maintenance. Whether you're an experienced contractor needing support with contract upkeep or a prospective contractor looking to acquire a GSA Schedule, there’s always more to learn about the GSA Multiple Award Schedule program and selling goods and services to the government. Our experienced team is here to help your company with both GSA Schedule acquisition and ongoing contract maintenance.