Granting billing access to IAM users

If you are the root account holder, then IAM users in that a/c by default will not be able to view billing or account preference information (even if you give them Administrator access). As mentioned in the AWS docs:-

http://docs.aws.amazon.com/awsaccountbilling/latest/aboutv2/control-access-billing.html

the below checkbox under (My Account -> Account Settings) needs to be enabled if you want IAM users to view billing. This can further be restricted by user level IAM inline policies or group level policies.