Step 1: Get the 12 digit number of the Destination AWS Account Sign in to the AWS Management Console for the destination AWS account. In the navigation bar, click Support , and then click Support Center . The account number (for example, 222222222222 ) is displayed in the upper-right corner of the Support Center. Step 2: Attach the policy to Source S3 Bucket The Bucket policy set up in the source AWS account. Do NOT forget to change the account number and bucket name in the below policy, otherwise, it will not work For help on setting the ACL check here { " Version " : " 2012-10-17 " , " Statement " : [ { " Sid " : " DelegateS3Access " , " Effect " : " Allow " , " Principal " : { " AWS " : " 057682336657 " }, " Action " : [ " s3:ListBucket " , " s3:GetObject " ],