Simsim
Simsim founded GSTCal and builds, writes and checks every calculator and guide on the site. Each GST formula is tested against hand-worked examples, and each explanation is written from the Australian Taxation Office's published guidance, with the sources listed on the page.
Founder and editor
I test every calculation against hand-worked examples, write the explanations from the ATO's own guidance, and review the pages when GST rules change. GSTCal isn't a government agency, and the site gives general information, not personal tax advice.
- Subject areas
- Australian GST calculations, Small business tax basics
- Profile last reviewed
- 8 November 2026