FAR 52.211-10—Commencement, Prosecution, and Completion of Work.
Plain-English Summary
FAR 52.211-10 is the standard construction clause that sets the contractor’s basic time obligations for starting, actively performing, and finishing a fixed-price construction project. It addresses when work must commence after the notice to proceed, the duty to prosecute the work diligently, the deadline for completing the entire project ready for use, and the requirement that completion time includes final cleanup of the premises. It also tells the contracting officer how to state the completion requirement—either as a number of calendar days after notice to proceed or as a specific calendar date—and it includes Alternate I for situations where the completion date is tied to an assumed notice-to-proceed date. In practice, this clause is the primary schedule-control provision in many construction contracts, and it gives the government a clear basis for measuring delay, enforcing performance, and evaluating whether the contractor is on track. For contractors, it creates a firm schedule obligation that can affect staffing, subcontracting, material procurement, and exposure to liquidated damages or default remedies if the work is late. For contracting officers, it is a key drafting tool that must be coordinated with the solicitation, award timing, bonding requirements, and any special ordering structure for indefinite-delivery construction contracts.
Key Rules
Applies to fixed-price construction
This clause is prescribed for solicitations and contracts when a fixed-price construction contract is contemplated. It is the standard schedule clause for construction work, and the contracting officer may adapt it for orders under indefinite-delivery construction contracts.
Start work promptly
The contractor must commence work within the number of calendar days stated in the contract after receiving the notice to proceed. The contracting officer must insert either a day count or a specific calendar date, depending on how the contract is structured.
Diligent prosecution required
The contractor must prosecute the work diligently, meaning it must actively and continuously pursue performance rather than allow avoidable delays or idle periods. This requirement supports government oversight of progress and can be used to address slow or inadequate performance.
Complete by the stated deadline
The contractor must complete the entire work ready for use by the completion date or within the stated number of days. The completion time includes final cleanup of the premises, so the project is not complete until the site is fully ready for use and cleaned up.
Completion date may be calendar-based
The contracting officer may state completion as a specific calendar date instead of a number of days after notice to proceed. This gives the government a fixed end date, but it requires careful drafting to account for when the notice to proceed is actually issued.
Alternate I adjusts for late notice to proceed
If the completion date is based on the assumption that the contractor will receive the notice to proceed by a certain date, Alternate I extends the completion date by the number of days the notice is delayed beyond that assumed date. The extension does not apply to delay caused by the contractor’s failure to execute the contract or provide required performance and payment bonds on time.
Responsibilities
Contracting Officer
Insert the required commencement and completion terms, choosing either a day count or a calendar date; issue the notice to proceed; decide whether Alternate I is needed; and ensure the clause is properly tailored for the contract structure, including any indefinite-delivery construction ordering arrangement.
Contractor
Begin work within the required time after receiving the notice to proceed, continuously and diligently prosecute the work, complete the entire project ready for use by the required date, and include final cleanup in the completion effort. If Alternate I applies, the contractor must also understand that late notice-to-proceed relief may be limited if the delay was caused by its own failure to execute the contract or furnish bonds on time.
Agency/Government
Administer the schedule, monitor progress, and determine whether the contractor is meeting commencement, diligence, and completion obligations. The agency must also coordinate notice-to-proceed timing with award, bonding, and any project-specific schedule requirements.
Practical Implications
This clause is one of the main tools the government uses to control construction schedule performance, so the notice to proceed date and completion date must be managed carefully from award through closeout.
Contractors should treat the commencement deadline as a hard mobilization requirement, not just a planning target; delays in staffing, subcontracting, or material procurement can quickly create noncompliance.
The phrase "diligently" can become important in disputes even when the final completion date has not yet passed, because the government may challenge slow progress or inactivity before the deadline.
Completion is not just substantial physical completion; the contract requires the entire work to be ready for use and the site cleaned up, so punch-list work and final cleanup matter.
When the completion date is tied to an assumed notice-to-proceed date, contractors should watch for bond-execution delays and award timing issues, because Alternate I may extend the date only in limited circumstances.
Official Regulatory Text
As prescribed in 11.404 (b) , insert the following clause in solicitations and contracts when a fixed-price construction contract is contemplated. The clause may be changed to accommodate the issuance of orders under indefinite-delivery contracts for construction. Commencement, Prosecution, and Completion of Work (Apr 1984) The Contractor shall be required to (a) commence work under this contract within _________ [ Contracting Officer insert number ] calendar days after the date the Contractor receives the notice to proceed, (b) prosecute the work diligently, and (c) complete the entire work ready for use not later than ______________ .* The time stated for completion shall include final cleanup of the premises. * The Contracting Officer shall specify either a number of days after the date the contractor receives the notice to proceed, or a calendar date. (End of clause) Alternate I (Apr 1984) . If the completion date is expressed as a specific calendar date, computed on the basis of the contractor receiving the notice to proceed by a certain day, add the following paragraph to the basic clause: The completion date is based on the assumption that the successful offeror will receive the notice to proceed by _______________ [ Contracting Officer insert date ] . The completion date will be extended by the number of calendar days after the above date that the Contractor receives the notice to proceed, except to the extent that the delay in issuance of the notice to proceed results from the failure of the Contractor to execute the contract and give the required performance and payment bonds within the time specified in the offer.