KETHEA is funded by the Hellenic Ministry of Health and Social Solidarity, by its workshops and production units, and by private donations and EU programs. State funding has to cover a significant part of KETHEA's expenditure, as the organization provides its services to substance abusers and their families free of charge and does not seek a contribution from social security organizations.

KETHEA’s treatment costs are significantly reduced thanks to the work undertaken by volunteers, especially the voluntary Family Associations associated with each of its therapeutic programs, and by the fact that it does not employ auxiliary staff or security personnel. The tasks associated with the daily running of the therapeutic programmes (such as cleaning, preparing meals, making repairs, shopping etc.) are performed by the members themselves, and comprise an integral part of the therapy.

Although it is not under a legal obligation to do so, KETHEA employs chartered accountants to carrie out annual audits of its financial statements. Its annual reports are forwarded to the Hellenic Ministry of Health and Social Solidarity, and to the General Accounting Office.