Section 13.21 - Contract clause(a) The contractor, as a condition of payment, shall abide by the terms of the applicable Executive Order paid sick leave contract clause referred to in § 13.11(a) .(b) The contractor shall include in any covered subcontracts the applicable Executive Order paid sick leave contract clause referred to in § 13.11(a) and shall require, as a condition of payment, that the subcontractor include the contract clause in any lower-tier subcontracts. The prime contractor and any upper-tier contractor shall be responsible for the compliance by any subcontractor or lower-tier subcontractor with the requirements of Executive Order 13706 and this part, whether or not the contract clause was included in the subcontract.