The Tax Office is deciding whether an anti-wind farm group linked to former Liberal MPs should retain its favourable tax treatment.
The Waubra Foundation has been classified a "health promotion charity" by the Tax Office, meaning its "principal activity is promoting the prevention and control of disease in humans".
It has also been granted deductible gift recipient status by the Australian Taxation Office, and donations of more than $2 to it are tax deductible.
In the ATO's words, obtaining the status is a "relatively difficult process, for obvious reasons".
Donations to Waubra have helped fund legal challenges against wind farm developments.
Former health minister Michael Wooldridge is a director of Waubra, and former MP Alby Schultz is its patron.
The foundation says its main aim is to "educate others about the known science relating to the adverse health impacts of infrasound and low-frequency noise".
The health effects of wind farms has become an increasingly vexed question in the countryside, where there are dozens of farms operated by companies including AGL and Origin Energy.
Sydney academic Simon Chapman says the number of reports of health problems linked to wind farms has reached 216.
He has argued that bad publicity about the farms makes it more likely that people will report feeling sick around them.
"Wind turbine syndrome" - health problems ranging from headaches, dizziness and insomnia, purportedly the result of the turbines' low-frequency sounds - is not recognised as a medical condition.
But, said Sarah Laurie, Waubra chief executive: "Whatever label is given to that range of symptoms, whether it is 'wind turbine syndrome' or 'annoyance' or 'infrasound and low-frequency noise syndrome' or something else, the facts remain that there are serious health problems occurring in some people which have been known to the wind industry for nearly 30 years."
A spokesman for Greens senator Richard Di Natale expected the review of Waubra's status by the Tax Office and the Australian Charities and Not-for-profits Commission to be finished this month.
The Tax Office has refused to comment, but described Waubra's situation as "curious".
In a recent Senate estimates hearing, Senator Di Natale asked how the Tax Office determined that an illness a group purported to prevent was actually an illness.
Tony Poulakis, the ATO's assistant commissioner, small and medium enterprise, replied: "I have to admit to not knowing the procedure in which we made those determinations well enough to answer your question."
Chris Jordan, ATO commissioner, responded: "It does sound a curious situation, but we will certainly take that on notice."