Allowable vs. Unallowable Costs in Government Contracts

Federal cost reimbursement contracts require contractors to classify every expenditure as either allowable or unallowable before billing the government. This distinction, governed primarily by Federal Acquisition Regulation (FAR) Part 31, determines which costs may be included in contract billings, overhead rates, and incurred cost submissions. Misclassifying unallowable costs as allowable can trigger repayment demands, penalties under the False Claims Act, and audit findings by the Defense Contract Audit Agency (DCAA) — making this one of the highest-stakes compliance areas in federal contracting.

Definition and scope

An allowable cost is a cost that meets the criteria established under FAR 31.201-2 and may therefore be billed to, or reimbursed by, the federal government. An unallowable cost is one that fails at least one of those criteria and must be excluded from any billings, indirect cost pools, and cost proposals — even if the expense was legitimate and necessary for the contractor's business.

FAR 31.201-2 sets out five conditions that a cost must satisfy to be allowable:

1. Reasonableness — the cost does not exceed what a prudent person would incur under comparable circumstances (FAR 31.201-3)
2. Allocability — the cost is assignable to the contract in accordance with the benefit received (FAR 31.201-4)
3. Standards compliance — the cost conforms to any applicable Cost Accounting Standards (CAS) or, where CAS does not apply, to generally accepted accounting principles
4. Contract terms — the cost is not expressly excluded by the contract itself
5. FAR Part 31 limitations — the cost is not listed as unallowable under the specific cost principles in FAR Part 31

The Federal Acquisition Regulation overview provides broader context on how Part 31 fits within the full regulatory framework governing federal procurement.

How it works

In practice, allowability analysis occurs at two stages: during proposal pricing and during contract performance and billing.

At the proposal stage, contractors must exclude unallowable costs from cost estimates submitted for cost-type contracts. Including unallowable costs in a proposal certified under FAR 15.406-2 can constitute a defective pricing violation, potentially triggering price adjustments under the Truth in Negotiations Act (10 U.S.C. § 3701 et seq., as codified after the NDAA 2021 recodification).

During performance, contractors must segregate unallowable costs in their accounting systems. FAR 31.201-6 requires that unallowable costs — and costs that are directly associated with unallowable costs — be identified and excluded from any billing or claim submitted to the government. The DCAA tests this segregation during incurred cost audits; a finding that unallowable costs were included in indirect pools can result in questioned costs and mandatory refunds.

Incurred cost submissions filed annually under FAR 52.216-7 are a primary audit trigger for allowability reviews.

Common scenarios

The following cost categories are expressly listed as unallowable under FAR Part 31:

• Advertising and public relations costs (FAR 31.205-1) — costs for promotional materials, brand advertising, and institutional image campaigns are unallowable; recruitment advertising directly tied to contract performance is allowable
• Alcoholic beverages (FAR 31.205-51) — categorically unallowable regardless of the business context
• Bad debts (FAR 31.205-3) — losses from uncollectible accounts are unallowable
• Contributions and donations (FAR 31.205-8) — charitable contributions are unallowable even when made in the contractor's name
• Entertainment costs (FAR 31.205-14) — costs for amusement, diversion, or social activities are unallowable
• Fines and penalties (FAR 31.205-15) — costs resulting from violations of law are unallowable
• Interest expense (FAR 31.205-20) — financing costs and interest on borrowed capital are unallowable
• Lobbying costs (FAR 31.205-22) — costs to influence legislation or regulatory action are unallowable

By contrast, allowable cost categories commonly include direct labor, fringe benefits allocated per an established plan, material costs, subcontractor costs, applicable overhead, and independent research and development (IR&D) costs subject to the ceilings negotiated under forward pricing rate agreements.

Decision boundaries

The allowable/unallowable distinction is not always binary. Three boundary conditions create recurring classification challenges.

Partial allowability. A single cost may be partially allowable. Under FAR 31.205-46, travel costs are allowable up to the federal per diem rate; the portion exceeding that rate is unallowable. Similarly, compensation costs under FAR 31.205-6 are allowable only up to the benchmark established by the Office of Personnel Management for senior-level federal employees — a cap that the FAR Council adjusts periodically.

Direct association rule. FAR 31.201-6(c) extends unallowability to costs that are "directly associated" with an expressly unallowable cost. If entertainment is unallowable, the travel costs incurred solely to attend an unallowable entertainment event are also unallowable. This rule requires contractors to trace cost relationships, not just categorize individual line items.

Expressly unallowable vs. determined unallowable. FAR 52.242-3 draws a distinction between costs that are "expressly unallowable" — identified as such in FAR Part 31 by name — and costs "determined to be unallowable" through a contracting officer's judgment. Penalties under FAR 42.709 apply only when expressly unallowable costs are included in a final indirect cost rate proposal; the penalty equals the amount of the unallowable cost (FAR 42.709-1), and a second offense can double that amount.

Contractors operating on cost-reimbursement vehicles — including cost-plus-fixed-fee, cost-plus-incentive-fee, and time-and-materials contracts — carry the highest exposure because every dollar billed must withstand audit scrutiny. Fixed-price contractors are generally not subject to FAR Part 31 cost principles unless the contract explicitly incorporates them, a distinction detailed in the government contract profit and fee structures page.

The false claims act and government contractors framework governs the most serious consequences when unallowable cost misclassification rises to the level of a knowing misrepresentation — with civil penalties that, as of the 2023 Federal Civil Penalties Inflation Adjustment, range from $13,946 to $27,894 per false claim (DOJ Civil Division, False Claims Act statistics).

Contractors seeking a foundational map of where cost allowability fits within the broader compliance landscape can start at the government contractor authority home page, which organizes the full range of regulatory and contracting topics covered across this reference network.