Evaluating the Impact of Bulk Billing Policy Changes on Mental Health Service Utilisation in Australia (2019–2023): A Time Series Analysis (Preprint)

BACKGROUND Between 2019 and 2023, Australia introduced several bulk billing policy reforms, including increased financial incentives and expanded telehealth access, to improve mental health service utilisation. However, overlapping reforms and rising operational costs have made their overall impact unclear. OBJECTIVE The study was conducted to evaluate the impact of bulk billing changes (from 2019 to 2023) on mental health service use and access disparities across states and territory in Australia. METHODS We conducted an Interrupted Time Series (ITS) analysis using Generalised Linear Mixed Models (GLMMs) and Hurdle Models to assess changes in utilisation of three mental health services—fully covered in-person (MBS 2715), partially covered in-person (MBS 281), and fully covered telehealth (MBS 92116) —from October 2018 to December 2022. Major policy interventions in April 2020 and July 2021 were evaluated. RESULTS Following the April 2020 incentive increase, in-person services (MBS 2715) showed a significant upward trend (β = 0.05, p = 0.031). In contrast, the July 2021 reduction in telehealth incentives was associated with a 7.7% decline in the odds of telehealth service use (MBS 92116), based on modelled estimates (Logistic: β = -0.08, p = 0.010). Utilisation remained lower among men and older adults. CONCLUSIONS Bulk billing reforms significantly affect mental health service utilisation, with affordability and incentive stability shaping access patterns. Policy shifts that reduce incentives can rapidly decrease usage, particularly in telehealth. Sustainable reform should combine consistent funding with targeted strategies to address demographic and geographic disparities.