Data on Sri Lanka’s revenue to GDP ratio is available from 1959 onwards.
The average tax to GDP ratio from 1959 to 2021 is 16%. In 2021 the tax to GDP ratio dropped to 8%, which the lowest ratio since 1959 and is half of the average ratio.
Source : Statistical Appendix , Central Bank of Sri Lanka Annual Report 2021. Available at < https://www.cbsl.gov.lk/sites/default/files/cbslweb_documents/publications/annual_report/2021/en/16_S_Appendix.pdf >