Almost every federal acquisition requires one, yet the Independent Government Cost Estimate is one of the most consistently weak documents in the procurement file. The FAR expects an IGCE for most actions — it underpins the funding request, anchors price reasonableness, and (above the simplified acquisition threshold) is part of the documentation a reviewer or auditor will pull first. But in practice, a large share of IGCEs are a single padded number in a spreadsheet cell with no traceable basis behind it.
That is the difference between an estimate and a defensible estimate. A defensible IGCE is one where every dollar can be traced to a labor category, a quantity, a rate, and a source — so that when a vendor's proposal comes in 30% higher, you can say exactly why the government's number is what it is, and where the gap is.
Here is how to build one, the way a contracting officer would.
An IGCE is the government's independent projection of what a requirement should cost, built before proposals are received and without reference to any vendor's pricing. It serves three jobs at once:
To do all three, the estimate cannot be a lump sum. It has to be decomposed — broken into the cost elements that make it up, each with its own basis. That decomposition is what makes it independent (you built it from the ground up, not from a vendor's quote) and defensible (each piece is traceable).
The common failure modes are predictable, and reviewers know them:
Each of these is a gap a protest, an auditor, or a skeptical program reviewer can drive a truck through. The fix for all of them is the same: a documented methodology.
A defensible estimate is built from a small number of cost elements, each priced independently and documented in a basis of estimate.
Identify the specific labor categories the work requires (not generic "consultant" — Tier 1 Help Desk Technician, Program Manager, Cybersecurity Analyst, and so on), then for each one: how many you need, how many hours per period, and the fully-burdened hourly rate.
"Fully burdened" matters. A defensible labor rate includes direct labor plus fringe, overhead, G&A, and (for fixed-price and T&M work) profit. The most defensible public source for these is the GSA CALC+ tool, which publishes ceiling rates from real GSA Schedule contracts by labor category. Pull the rate, note the percentile you used (median is the usual starting point), and record how many contractor records it was drawn from. That is a citation a reviewer can verify.
Subcontracted services are still labor. If your scope subcontracts work — imaging, monitoring, an on-site support team — model it as labor categories with hours and rates, not as an opaque "subcontract" lump sum. The defensible price of subcontracted work is labor × hours × rate, whoever performs it.
List the non-labor items: hardware, software licenses, equipment, materials, travel. The discipline here is the inverse of the labor mistake — these lines are goods only, never labor-inclusive assemblies. Itemize into real, purchasable products with quantities ("Business laptop × 500"), because a reviewer can verify a product price; they cannot verify a blended "$/SF installed" figure. Price each from a real listing — a manufacturer page, a B2B reseller, GSA Advantage, or a cooperative-contract price list — and cite it.
If the work requires travel, build it from GSA Per Diem rates for the location: M&IE and lodging per day, times days per trip, times trips per period, times travelers. Travel is reimbursable at cost — it carries no markup.
Multi-year estimates escalate. Apply a defensible annual escalation factor (commonly 2–3%) to each option period: Period N = base × (1 + rate)^(N−1). State the rate and the formula. One-time costs — equipment bought once, a transition-in crew — belong only in the base period and must not repeat into option years.
This is the narrative that ties the numbers to their sources: where labor rates came from and at what percentile, how materials were priced, the escalation assumption, the travel basis, and any staffing assumptions you made. If the estimate is for a non-federal buyer, the framing shifts (a state or local buyer leans on cooperative-contract pricing rather than FAR price-reasonableness language) — but the discipline is identical. A reader should be able to reconstruct your total from the basis of estimate alone.
Done by hand, that process is real work — looking up labor categories, pulling current rates, sourcing material prices, building the escalation table, and writing the methodology. It is exactly the kind of structured, source-driven task that is now worth automating.
We built a free tool for it. ArcPrice takes a plain-English description of what you're buying and drafts the whole estimate: it identifies the labor categories, pulls live GSA CALC+ rates, sources real market prices for materials with cited links, applies escalation across your option periods, benchmarks the total against comparable federal awards, and writes the basis of estimate for you — then exports it to Excel and PDF. It works for federal, state & local, and commercial work, and it's free to use.
It won't replace a contracting officer's judgment — you still review the categories, confirm the quantities, and verify the prices — but it removes the hours of mechanical assembly and gives you a defensible, fully-decomposed estimate to start from instead of a blank spreadsheet.
ArcPrice drafts labor, materials, and escalation with live GSA rates and cited market prices, then writes the basis of estimate. No login, no credit card.