https://bigdigit.atlassian.net/browse/WG-687

Cost Categories are set against a client. Cost Types are entered against a Cost Category.

Any number of cost categories can be added against a client, but cost categories cannot be duplicated.

Domain Model

https://bigdigit.atlassian.net/wiki/spaces/TD/pages/3458760745

Validation

Cost Categories cannot be duplicated against a client.