Abstract Purpose: This study examines the comparability of audit firms’ transparency reports disclosures, assessing informational value and comparability across audit firm types over an eleven-year period. Design/methodology/approach: The study uses computational text analysis on a sample of 194 transparency reports from 20 Australian audit firms from 2013 to 2023. The study analyses the report's content using the Australian Securities and Exchange Commission (ASIC) framework and examines its disclosure content, tone and readability. Findings: The transparency reports exhibit significant differences in content, tone, and readability across audit firm types. In terms of ASIC requirements, Big 4 firms provide the most detailed disclosures (64%), followed by large non Big 4 firms (57%), while medium firms disclose only 33%, limited to the ASIC mandated requirements. In terms of tone, Big 4 reports use more positive, evidence based, and collective language than other audit firms. All audit firms' reports are low readable; however, large non Big 4 firms produce more readable reports than Big 4 and medium non Big 4 firms. The disclosure scope expanded after 2019, introducing themes on Environmental, Social and Governance (ESG), digitalisation, culture, and employee wellbeing, with increased use of environment related and employee focused images. Originality/value: This study provides one of the first longitudinal studies on the informational content, tone, and readability of Australian audit firm transparency reports. It demonstrates how differences in disclosure communication influence the comparability and informational value of transparency reports, providing regulators and stakeholders with a basis for evaluating audit firm accountability.