承诺函是贷款人承诺向借款人提供资金的信函。如果贷款人决定发放贷款，就向申请人发出一份承诺函，承诺函在30—60天内有效。贷款人在承诺函中要求借款人支付承诺费。如果借款人决定不购买房产，或用其他的融资途径来购买房产，那么所支付的承诺费就损失了。因此，承诺函写明，申请人通过支付一定的费用，可以有权利而没有义务要求贷款人以一定的利率和期限提供资金。

在法律文件中英互译中，承诺函也是很常见的一种法律文件类型，我们一般将其英译为“ A letter of commitment ”，如果遇到title比较具体的，例如《关于*****事项的承诺函》，一般处理为 A letter of commitment on ... 。

以下是在译问词典中提取的双语例句供参考：

1.

第二十四条牵头行经与借款人协商，向潜在参加银行发出银团贷款邀请函，并随附贷款条件清单、信息备忘录、保密承诺函、贷款承诺函等文件。

Article 24 the lead arranger , after consultations with the borrower , will send invitations to potential participating banks , together with documents such as the syndicated loan term sheet , memorandum , confidentiality agreement and letter of commitmentetc.

2.

甲方应组织其成员单位向协办行提供《资金池授权加入承诺函》（详见附件3），《资金池授权加入承诺函》经乙方审查通过后，该账户才正式加入资金池服务体系。

Party A shall organize its member units to provide the Assisting Branch with the Letter of Commitment on Authorized Incorporation into the Cash Pool (see Appendix 3 for detail), and upon examination and approval of Party B, such account can be officially incorporated into the cash pool service system.

3.

证券公司对申请文件真实性、准确性、完整性承担责任的承诺函，并应由全体董事签字；

A letter of commitment made by the securities company promising that it will be responsible for the authenticity, exactness and completeness of the application documents, which shall be affixed with the signatures of all the directors;