Objections need to be made within a specified time following issue of a tax assessment by a commissioner.
Will a late objection be accepted by the commissioner of taxation?
Late objections are permitted but only for a good reason which the taxpayer must establish. That is, to be certain the objection will be accepted, the objection needs to made within time.
60 days or four years from the assessment?
The good news, at least with objections against income tax assessments which are the most common, is that a taxpayer is allowed two years or four years from the issue of an original assessment to object and, in the case of an amended assessment (that is, an assessment altering an earlier assessment say following an ATO audit) the taxpayer has the later of the two or four year period from the issue of the original assessment or sixty days from the issue of the amended assessment to object.
The ATO has a useful aide memoir of objection time limits on their website. Unfortunately they frequently alter the url due to their frequent site makeovers and they do not use auto redirects so don’t rely totally on this link.
60 day time limit common for state tax assessment types
With state taxes specified times for objecting are largely unreformed which typically means that a sixty day time limit for submitting an objection applies to these types of assessments.
Extended time limits applying after an original income tax assessment
The two or four year time limit measured from the time of original income tax assessment varies with the type of taxpayer. In a nutshell a time limit of four years applies to taxpayers who run or participate as partners or beneficiaries of entities that are not small business entities.