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If you sell to the Department of War, two rulebooks govern every FAR-based contract you pursue, and your proposal has to satisfy both at once. The first is the FAR, the Federal Acquisition Regulation. The second is the DFARS, the Defense Federal Acquisition Regulation Supplement. Ask a room of defense contractors what the FAR vs DFARS difference actually is, and you will get confident, contradictory answers. That confusion is expensive because, in federal contracting, compliance shapes nearly every clause of the contract you’re pursuing.
The FAR is the government-wide rulebook for federal acquisitions. It governs how agencies buy, how contractors compete, and what terms flow into the resulting contract. If you do any federal work at all, civilian or defense, the FAR governs it.
It covers the full lifecycle: competition requirements, contract types, cost principles, subcontracting, contract administration, and termination. A contracting officer at any federal agency works from this same baseline. Experienced GovCon teams know the FAR.
The DFARS is the Department of War’s supplement to the FAR.
The DFARS adds requirements that defense contractors meet every day: cybersecurity obligations for covered defense information, domestic sourcing restrictions, specialty metals rules, export control considerations, and DoD-specific cost and pricing requirements. Where the DFARS speaks, its requirements are usually stricter than the FAR’s.
Both layers apply simultaneously, and the contract you win will incorporate clauses from each.
Complicating things further, the FAR is currently being rewritten. Under the Revolutionary FAR Overhaul, agencies have already adopted streamlined FAR parts through class deviations, the FAR Council began formal rulemaking in 2026, and DoD is revising the DFARS in parallel. For now, your existing contracts may sit under the original FAR, the deviation version, or eventually the final rule, so every new solicitation is worth checking clause by clause.
In a live pursuit, the two rulebooks appear in the same solicitation, and your team has to track both.
Your compliance matrix has to track every instruction and requirement in the RFP, and your team has to account for the clauses in Section I, including DFARS clauses that carry their own flow-down obligations to subcontractors. A requirement missed at the proposal stage becomes a performance obligation once the contract is signed, priced into a bid that never accounted for it.
The cost side works the same way. Proposals must meet specific evaluation criteria and support your pricing with a defensible basis of estimate. Evaluators read your cost proposal against the regulatory structure that produced it, and inconsistencies between your narrative, your pricing, and your clause positions are exactly what evaluators flag.
Most contractors treat FAR and DFARS compliance as a review step: write the proposal, then have someone check it. Government RFPs hold strict compliance standards, but under deadline pressure, teams reviewing a long, clause-dense proposal by hand still miss things.
Stronger teams build compliance into the draft itself. The first version your team reviews already reflects the regulatory structure of the pursuit. Reviewers then spend their time on judgment calls and differentiation, not on gaps the draft should never have contained.
Building for both rulebooks is the premise behind UnifiedRespond™, Rohirrim’s AI-native platform for government contractors, now extended by GrowthEngine from first notice to final submission. UnifiedRespond is a purpose-built RFP automation platform that produces a high-quality, compliant first draft with human-governed AI, mapped to the solicitation’s requirements. Proposal teams still double-check every clause, but they start from a draft that considers compliance from the beginning and can spend their hours on verification and differentiation. Teams using it report 20X productivity gains, 35% lower proposal costs, and 40% more RFP responses with the same team.
Every defense pursuit operates inside the FAR and DFARS. The teams that win have that structure in the draft from the start.
See how UnifiedRespond builds compliant first drafts for government contractors. Book a demo at rohirrim.ai.
