Rent Control governs how much the rent of a unit can be raised. In DC typically the amount that the rent can be raised is based on CPI index. We recommend that you consult the Rent Control Administrators Office with any questions relating specifically to the subject as they are the authority.

Meanwhile we recommend you read our Blog article on the subject as well as it gives more perspective on the subject:
http://blog.rentjiffy.com/2011/09/02/faqs-on-dc-rent-control-%E2%80%93-part-one/