 The European Comparative Effectiveness Research on Internet-based Depression Treatment E-COMPARED in Poland aims to compare the clinical and cost-effectiveness of blended CBT for adults with major depressive disorder MDD with treatment as usual TAU. The trial will be conducted in routine mental health care in Poland, and is a part of the bigger project funded by European Commission Grant Agreement No: 603098. In this randomized controlled trial, a total of 150 patients with MDD will be assigned to one of two conditions: 1 blended CBT, 2 TAU. Respondents in both conditions will be followed until 12 months after baseline measures will be taken at baseline, 3 months, 6 months and 12 months. 