Lucas will stay on until then to support new permanent secretary Sir Bob Kerslake in implementing the changes to the top structure announced following last month's comprehensive spending review.
Lucas joined the DCLG in September 2009 and was acting permanent secretary from June until November. "It was a great privilege to serve in the post until Kerslake's arrival at the start of this month," she said.
"Kerslake has a deserved reputation for leading organisations through times of significant change. I am looking forward to working alongside him over the next few months as we start the process of becoming a smaller but stronger department," she added.