Found a figure that is wrong
This is the most useful thing you can send. Tell us which page, which number, and what you think it should be — and if you have the source, the link to it. Every figure on this site is meant to trace to legislation or an authority’s own published material, so a correction with a source attached can be checked and fixed the same day.
Corrections are welcome even when they are inconvenient. A calculator that is quietly wrong is worse than one that does not exist.
Want a calculator that is not here
Tell us what you were trying to work out and what you ended up doing instead. That second part is the useful half — it says what the gap actually is, which is usually not what the tool name suggests.
What we cannot do
We cannot give advice about your situation. Not as a policy of caution — the site is not run by a registered tax agent or BAS agent, and advising on your circumstances would be both unhelpful and, in some cases, something only a registered practitioner may do. Questions about how a page works out its figures are very welcome; questions about what you should do are for your accountant or the ATO.
The methodology page answers most “how did you get that” questions, and the about page says who is behind the site.