As prescribed in 16.603-4(b)(1), The contracting officer shall include in each letter contract the clauses required by this regulation for the type of definitive contract contemplated and any additional clauses known to be appropriate for it.
(b) In addition, the contracting officer shall insert the following clauses in solicitations and contracts when a letter contract is contemplated: (1) The clause at 52.216-23, Execution and Commencement of Work, except that this clause may be omitted from letter contracts awarded on SF 26;
Execution and Commencement of Work (Apr 1984)
The Contractor shall indicate acceptance of this letter contract by signing three copies of the contract and returning them to the Contracting Officer not later than _______________ [insert date]. Upon acceptance by both parties, the Contractor shall proceed with performance of the work, including purchase of necessary materials.
(End of clause)