Tenant claim I cannot disclose there forwarding address to utility companies without there consent

Tenancy Types and Management

I have a tenant who is about to leave my property, who claims that I am not allowed to disclose their forwarding address, without their permission. Surely this does not include Councils, or utility companies, who may want to recover any unpaid debt? I am concerned because in the past I have been pursue for unpaid Council tax that a tenant has not paid. What is my position here?