How to Submit GSA MOD Requests: A Practical Walk-through

If your organization holds a General Services Administration (GSA) Schedule contract — often simply called a “GSA contract” — knowing how to process modification (mod) requests is essential. This article walks you through the process step by step, combining formal federal procurement guidance with practical insights from Capitol 50’s experience supporting federal contractors.

In GSA parlance, a “mod” means a contract modification — a formal change to your awarded contract under the GSA Multiple Award Schedule (MAS).

Let’s get into how to submit a GSA mod request effectively.

1. Why Mods Matter

Your MAS contract is not static. Over time, you may need to:

• Add or delete Special Item Numbers (SINs) to reflect new offerings or market direction.
• Add or remove products/services under existing SINs.
• Update pricing, terms and conditions, addresses, partnering arrangements, authorized negotiators, and so on.
• Respond to periodic mass modifications (mass mods) issued by GSA.

According to GSA’s “Modification and Mass Modification Guidance”, changes to your contract that require a mod include: products, services, prices, terms & conditions, administrative info (addresses, authorized negotiators), key personnel, etc. 

Failure to process required mods (or mass mods) can jeopardize your contract’s compliance, your access to GSA tools, and ultimately your ability to win federal business. 

2. Know the Key Terms & Tools

Before you dive into submitting, get familiar with a few core terms:

• SIN number / SINs: These are the Special Item Numbers under your contract that define which goods or services you can offer. If you want to add a new SIN, that’s a specific type of modification.
• eMod / eOffer: GSA’s online system through which contractors submit mod requests. GSA will only consider contractor-initiated modifications via the eMod system. 
• Mass Modifications (Mass Mods): Periodically, GSA updates its solicitation terms via a mass mod, which all contractors must accept within a timeframe (often 90 days). Your own mod requests may be held up if you haven’t accepted outstanding mass mods. 
• Novation (FAR/GSAR 42.1204/42.1205): If your business undergoes structural change (merger, acquisition, name change, transfer of ownership), a novation mod may be required. The GSA mod guide includes a section on novation agreements. 
• Most-Favoured-Customer Clause / Basis of Award: When you hold a GSA contract, your prices are tied to the discount relationship you offered at award (Basis of Award or BOA). For price mods, understanding your “most favourable customer” pricing is key. 

3. High-Level Steps: How To Submit a Mod

Here’s a firm-but-practical walkthrough of submitting a mod request:

Step 1 – Determine the type of mod you need

Ask: What change is required? Some common types:

• Administrative (address change, authorized negotiator change)
• Add/delete items or services
• Add/delete SINs
• Price increase or decrease (including Economic Price Adjustment)
• Novation or transfer of contract
• Cancellation of all or part of the contract

Each type has its own checklist. 

Step 2 – Verify you are current with all outstanding mass mods

You’ll want to log into GSA’s Mass Mod portal and check whether your contract has any outstanding mass mods. If you haven’t signed them, GSA may not process your new mod request. 

Step 3 – Gather required documentation and templates

The mod guide spells out what you need for each type. For example:

• Cover letter on company letterhead, signed by authorized negotiator
• Price Proposal Template (PPT) for additions, price changes, etc. 
• Updated Commercial Price List, product literature, technical information
• For adding a SIN: narrative explaining how offerings fall within scope of new SIN 

Step 4 – Log into eMod and submit

Using your authorized negotiator credentials, log into the eOffer/eMod system, upload the mod request, attach required documents, and hit submit. 

Step 5 – Monitor status & respond to CO/CS

Once submitted your mod request, the contracting officer (CO) or contracting specialist (CS) will review. You may need to respond to clarification requests. Timing varies — many mods take 30-60 days; administrative mods may take 2-3 weeks. 

Step 6 – Upon approval: implement changes

Once the mod is executed, you must upload your updated contract price list (via Schedules Input Program — SIP) or update your GSA Advantage!® catalog, if applicable. Make sure your contract file and catalog reflect the approved changes. 

4. Common Pitfalls to Avoid

• Attempting to submit a mod while mass mods are still outstanding.
• Submitting incomplete documentation — e.g., wrong version of PPT, missing cover letter, incomplete price list. 
• Proposing items or SINs outside the scope of your contract. 
• Mixing too many different types of changes in a single mod when specialization is needed (e.g., adding SINs, changing pricing, and deleting services in one). The guide recommends separating high-complexity items. 
• Forgetting to update authorized negotiators or delegated agents when your internal team changes — this can delay ability to submit or sign mods.

5. How Capitol 50 Helps

At Capitol 50, we work side-by-side with contractors to manage their GSA schedule lifecycle — including mods. If you’re unsure where you stand or want to streamline your contract administration, our services can help.

• For help with mod workflow and contract maintenance: see our GSA Contract Assistance page
• If you want a full diagnosis of your contract’s health, start with a free audit

6. Final Thoughts

Submitting a mod request for your GSA contract isn’t optional, it’s a necessary part of keeping your contract current, valid, and competitive. Think of your GSA contract as a living document: you must actively manage its evolution, not just leave it on autopilot.

By understanding the types of mods, following the required documentation checklists, and staying current with mass-mods, you position your company to move smoothly as your offerings, pricing, or corporate structure change.

If you feel like you’re navigating these waters solo , let Capitol 50 serve as your compass. Book a free audit today and see where your contract stands.