Notice to Proceed
A formal, written notice from the owner authorizing the contractor to begin work, the document that officially starts the contract clock and the project schedule.
Why it matters
A contract can be fully signed and still not actually started: the notice to proceed is the specific trigger that starts counting toward the contract completion date. Starting work before it's issued, or an owner delaying it, both have real schedule and payment consequences.
On a real project
A contract calls for substantial completion 300 calendar days after notice to proceed. The owner issues that notice on March 1st, which means the completion date isn't tied to the contract signing date back in January; it's tied to March 1st.
Who this matters most to
A Project Manager treats the notice to proceed date as the official start of the schedule they're accountable to. An Owner's Representative is often the one who actually issues it, timing it around financing, permits, or other conditions the owner needs cleared first.
Where this goes wrong
A contractor starts mobilizing and ordering materials as soon as the contract is signed, assuming that's the same as being authorized to start. The owner's financing falls through and the notice to proceed is delayed by two months, time and money the contractor already spent getting ready, with no formal authorization yet in place to bill against.