The Effective date and Duration Provision of Contract
一、以合同的生效日作为计算基准日
合同的生效日期在合同中非常重要，合同有效期一般都是以合同生效日作为基准日。合同中约定的当事人的权利义务享有或承担的起始日期都是以合同的生效日作为计算基准日。
如：
The BUYER shall make an advance payment of twenty million US Dollars ($2,000,000.00) to the SELLER within fifteen (15) days after the EFFECTIVE DATE of this PURCHASE and SALES CONTRACT.
买方在采购合同生效之日起15个工作日向卖方支付200万美元的预付款。
再如：The CONTRACTOR shall complete WORK within six (6) months after the EFFECTIVE DA TE of this DESIGN CONTRACT.
承包商自本设计合同生效之日起六个月完成工作。
本合同的有效期从合同生效日起算共_____年。
The Contract shall be valid for a period of ____ years from the Date of Effectiveness of the Contract.
如：This AGREEMENT shall commence on 7th, November 2007(“EFFECTIVE DA TE”) and shall maintain in full force and effect for three(3) years after the EFFECTIVE DATE。
本合同自2007年11月7日生效，有效期为三年。
为避免争议，一般在草拟合同时直接在合同中约定生效日，这种约定主要有以下几种表达方式：
例1 在定义部分，就“生效日”进行定义，如：
EFFECTIVE DA TE means the date on which the CONTRACT, after it is signed, be approved by the Ministry of Commerce of the People s Republic of China.
本合同生效日是中华人民国商务部批准之日。
例2 在合同中单列一个生效和有效期条款，比如：
This AGREEMENT shall commence with effect from 2nd October 2005(“EFFFECTIVE DA TE”) and shall continue until 2nd October 2010 unless terminated earlier in accordance with its terms and conditions.
本合同自2005年10月2日起生效，除非根据本合同约定条款终止，有效期至2010年10月2日。
二、在所附条件成立时为合同生效基准日
合同生效除了以具体的日期表述外，还可以约定以某个事件的发生或不发生作为其生效起点，相当于附条件，只有在所附条件成立时合同才生效，比如在一个中外合资合同中：
The AGREEMENT shall take affect upon the approval from the Ministry of Commerce of the People’s Republic of China.
本协议自中国商务部批准之日起生效。
再如：The AGREEMENT shall be deemed to have come into effect on the date when Italy has passed the LAW to cooperate with China concerning SERVICES.
当意大利方面依据法律批准了与中国的该服务时，本协议视为生效。
如合同自签字之日起经过六个月仍不能生效，则双方有权取消本合同。
If the Contract cannot come into force within 6 (six) months after the date of signing the Contract, both parties shall have the right to cancel the Contract.
This AGREEMENT shall take effect from the EFFECTIVE DATE provided that if the EEFFECITVE DA TE has not occurred by 30 November 2000, this AGREEMENT shall (unless the PARTIES agree otherwise) automatically terminate and each of the PARTIES hereto shall be released from any further obligations hereunder。
本协议生效日期为2000年11月30日，但如果届时未能生效，除非各方另有约定，本协议自动解除，各方互不承担责任。
采购协议的生效视另一个事件是否发生。为避免合同签订后其效力处于不确定的状态拖得太长，可在合同中约定，在某种条件下，合同永不生效，比如：
This AGREEMENT shall never take effect provided that PARTY B cannot get the approval from the competent authority within thirty (30) days after the signature of this AGREEMENT.
合同签订后30日乙方没有获得自己政府批准，则本协议自动解除。
三、关于合同有效期的持续期间
合同有效期的约定方式比较固定，通常为：