These are not official results or official code. There are many reasons why the official results may end up differently, some of which are listed below. This is provided with no warranty. Having said that, with the appropriate choice of rules (including emulation of electoral commission bugs) this tool provides exactly the same distribution of preferences for all provided elections, modulo table formatting.
This is a computer program, and like all computer programs, it probably contains errors. Errors either in my program or in the electoral commission's program could cause their results to be different. Similarly an incorrect understanding of the law, either by me or the appropriate electoral commission could cause a different result. There is no a priori reason to trust either, but having more than one available makes checking possible (although one error I found in my code was an identical error to one that the AEC had). One can also compare with other programs that do the same job like Grahame Bowland's program. These problems are particularly likely to come up in untested scenarios, such as the legal question of whether a party is eligible for above the line votes if all but one of their candidates are disqualified. Similarly, if a formal vote requires a certain number of numbers to be filled in, and one of those candidates ends up excluded, is it still a formal vote? Does a vote contribute to setting the quota if the first person voted for is excluded? I am not a lawyer.
Using this code and an earlier project, colleagues and I have discovered errors in the counts of the NSWEC in 2016, again NSWEC in 2016, Elections ACT in 2020, and the Australian Electroral Commission in 2021. These have all been acknowledged by the relevent electoral commissions, who have either fixed their program to match the legislation, or changed the legislation to match their program. This should not be taken as an indication that these electoral commissions are particularly bad. To the contrary, these are the electoral commissions who make the list of votes that they count available to the public, and this probably indicates that they are better than average.
The errors in the official counts are emulated by ConcreteSTV to be able to match the official transcripts perfectly, but a set of rules without said errors are also available.
Hackers may infiltrate or intercept the process, and change either my results or an electoral commission's result.
In some elections, there are ties, such as for the candidate with the lowest tally who should be excluded. Such ties are resolved in a variety of manners. For the federal senate, the AEC used to be given discretion but has recently changed to randomness. I generally cannot accurately pick this, although I generally include the decisions made by the electoral commission as part of the metadata for an election so they can be recreated.
In NSW state elections (not the NSW senators in the federal senate), rather than dealing with fractional votes in surplus redistribution, a random sampling of ballots is used. I cannot predict this, and the NSW EC does not make their method of choosing votes public. For this reason I do not include these elections on this site.
Some of the legislation covering vote counting is ambiguous. See for example NSW local government.