letter of indemnity　

letter of indemnity　赔偿保证书，认赔书，偿还税款保证书　

A written undertaking by a third party（such as a bank or insurance company），on behalf of one of the parties（the first party）to a transaction or contract，to cover the other party（the second party）against specific loss or damage arising out the action（or a failure to act）of the first party.Also called indemnity bond.