T&M vs Fixed Price — Contract Type Comparison
Time and Materials (T&M) and Firm-Fixed-Price (FFP) are the two most common contract types in government contracting, and they represent opposite ends of the risk spectrum. Choosing the right type — and knowing how to price each — can make or break your profitability.
This guide provides a detailed side-by-side comparison, explains when each type is appropriate, and shows you how to price both effectively.
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Side-by-Side Comparison
Definition
Government pays fixed hourly rates for each labor category plus actual material costs. Payment is based on hours worked, regardless of deliverables.
Government pays a single fixed price for a defined scope of work. Payment is based on deliverables, regardless of actual hours.
FAR reference
FAR 16.601 — Time-and-Materials
FAR 16.202 — Firm-Fixed-Price
Risk allocation
Shared. Labor rates are fixed (contractor risk), but hours are variable (government risk). Government bears the risk of scope uncertainty.
Contractor bears all cost risk. If costs exceed the fixed price, the contractor absorbs the loss. If costs are under, the contractor keeps the difference.
Government preference
Least preferred. FAR 16.601(d) requires a determination that no other contract type is suitable. Must include a ceiling price that the contractor exceeds at own risk.
Most preferred. FAR 16.101(b) states that FFP contracts are preferred for acquiring commercial items and when requirements are well-defined.
Profit visibility
Profit is embedded in the fixed hourly rates. The government knows your fully burdened rate but not your exact profit margin. Your margin depends on your actual costs vs. your rate buildup.
Profit is embedded in the total price and not separately disclosed. The government evaluates whether the total price is fair and reasonable without seeing your cost breakdown (for commercial items).
Invoicing
Invoice based on actual hours worked by labor category, supported by timesheets. Materials invoiced at actual cost. Monthly invoicing is typical.
Invoice based on deliverables accepted or milestones reached. Some FFP contracts allow monthly progress payments based on percentage of work completed.
Scope changes
Easier to accommodate scope changes because the government simply orders more or fewer hours. No modification needed for work within the overall scope.
Scope changes require a formal contract modification with price negotiation. Any work outside the original scope must be priced and approved before performance.
Audit exposure
Moderate. Government can audit timesheets and material costs. Labor rates themselves are pre-negotiated and not typically re-audited.
Minimal. For commercial items, the government does not audit costs. For non-commercial FFP, DCAA may audit the proposal but not ongoing costs.
When T&M Is Appropriate
Staff augmentation
When the government needs additional personnel working under government direction, T&M is natural. The agency controls the work, and the contractor provides qualified staff at agreed-upon rates. Hours fluctuate based on the agency's workload.
Undefined or evolving scope
When the government cannot define the full scope of work upfront — such as software maintenance, engineering studies, or advisory services — T&M avoids the risk of the contractor either padding the price for uncertainty or losing money on unforeseen work.
Emergency or rapid response
When the government needs immediate support and does not have time to define requirements precisely. Disaster response, cybersecurity incident response, and urgent IT fixes are common T&M use cases.
Research and development
When the outcome is uncertain and the level of effort cannot be predicted. T&M allows the government to fund R&D at a predictable rate without either party bearing undue risk from uncertain outcomes.
Important FAR requirement
FAR 16.601(d) requires a written determination that no other contract type is suitable before using T&M. The Contracting Officer must document why the work cannot be defined well enough for a fixed-price arrangement. Additionally, every T&M contract must include a ceiling price that the contractor exceeds at their own risk.
When FFP Is Preferred
Well-defined deliverables
When the government can precisely specify what it wants — a software system, a report, training curriculum, or a physical product — FFP is appropriate. The contractor knows what to deliver, and the government knows what it will pay.
Commercial products and services
FAR Part 12 commercial item acquisitions strongly prefer FFP. If you sell the same product or service commercially, the government expects to buy it at a firm price, just like your commercial customers do.
Mature, repeatable work
When the work has been done before and costs are predictable. Facilities maintenance with defined SLAs, recurring training, or production of known quantities are ideal for FFP because the contractor can estimate costs reliably.
Construction
Government construction contracts are almost always FFP. The scope is defined by drawings and specifications, and the contractor bids a firm price to complete the work. Change orders handle scope changes.
Risk Allocation Deep Dive
The fundamental difference between T&M and FFP is who bears the risk of cost uncertainty. Understanding this is critical for both pricing and managing your contracts.
The Risk Spectrum
The more risk the contractor takes, the higher the expected profit should be. FFP contracts should carry higher margins than T&M or cost-reimbursement contracts to compensate for the additional risk.
How to Price Each Type
Pricing T&M
Build fully burdened rates
Each labor category needs a rate that includes base salary, fringe, overhead, G&A, and profit. This single rate is what the government pays per hour.
Do not lowball rates
T&M rates are fixed for the contract period. If you set rates too low, you cannot raise them later (except at option year renewals). Unlike FFP, you cannot make it up on efficiency.
Include escalation for option years
Build in annual rate increases of 2-4% for option years to account for salary growth, benefit cost increases, and inflation.
Estimate hours conservatively
Even though hours are actual, you may need to provide a ceiling estimate. Base this on realistic projections, not best-case scenarios.
Pricing FFP
Define scope boundaries precisely
Your price assumes a specific scope. Any ambiguity in the SOW is a risk. Clearly state assumptions and exclusions in your proposal. Scope creep on FFP erodes your profit.
Build in management reserve
Include a contingency buffer (5-15% depending on risk) for unforeseen issues. Unlike T&M, you cannot bill for unexpected hours. Your reserve is your safety margin.
Price based on outputs, not inputs
The government pays for the deliverable, not your effort. If you can deliver efficiently, your profit margin increases. Focus on the value of the deliverable, not just cost-plus-fee math.
Higher profit margin for higher risk
FFP margins should be higher than T&M because you bear all cost risk. Target 10-20% profit on FFP vs. 6-10% on T&M. The riskier the scope, the higher the margin.
Which Contract Types Do Agencies Prefer?
The Federal Acquisition Regulation establishes a clear preference for fixed-price contracts. FAR 16.101(b) states that a firm-fixed-price contract provides maximum incentive for the contractor to control costs and should be used when the risk involved is minimal or can be predicted with an acceptable degree of certainty.
In practice, the contract type depends on the nature of the requirement. Agencies use FFP for well-defined deliverables and commercial items. They use T&M when they need flexible labor support and cannot define the exact scope of work.
Civilian agencies
Tend to use more FFP contracts, especially for IT modernization, software development, and professional services. GSA Schedule orders are predominantly FFP. OMB pressure to use FFP is strong at civilian agencies.
Department of Defense
Uses a mix of FFP and cost-reimbursement, with T&M common for engineering support and maintenance. Major weapons systems often use cost-plus contracts. Support services are increasingly FFP.
Intelligence Community
Heavy use of T&M and cost-reimbursement due to the classified and unpredictable nature of the work. Staff augmentation contracts in the IC are predominantly T&M.
Health & Human Services
Uses FFP for most IT and professional services. Research grants and cooperative agreements (not contracts) are the primary funding vehicle for HHS science programs.
Key Takeaways
FFP is appropriate when the scope is well-defined and the contractor can reliably estimate costs. It carries higher risk but should also carry higher profit margins.
T&M is appropriate when the scope is uncertain or evolving. Labor rates are fixed but hours are variable, creating shared risk between the government and contractor.
Price FFP based on deliverable value with a management reserve. Price T&M based on fully burdened labor rates with built-in escalation for option years.
The government prefers FFP per FAR policy, but will use T&M when circumstances require it. Read the solicitation carefully to understand which type is specified and price accordingly.
Your pricing strategy should account for the risk profile of the contract type. Higher risk (FFP) demands higher margins. Lower risk (T&M) allows competitive rates.
Research Contract Pricing on Bureauify
Use historical award data from FPDS and USAspending to see what agencies are paying for similar work. Compare T&M rates and FFP prices across comparable contracts to benchmark your pricing.