The UK Government's implementation in 2008 of the Improving Access to Psychological Therapies (IAPT) initiative in England has hugely increased the availability of cognitive behavioural therapy (CBT) for the treatment of depression and anxiety in primary care. Counselling for depression-a form of person-centred experiential therapy (PCET)-has since been included as an IAPT-approved therapy, but there is no evidence of its efficacy from randomised controlled trials (RCTs), as required for recommendations by the National Institute for Health and Care Excellence. Therefore, we aimed to examine whether PCET is cost effective and non-inferior to CBT in the treatment of moderate and severe depression within the IAPT service.