Apparently the story originates with an Argentinian investigative website:
https://www.elcohetealaluna.com/evasion-real/
They claim that she owns three plots of land in Rio Negro. The buildings on this land are -according to them- not registered with the provincial authorities. They claim that this is a way for her to avoid taxes.
The RVD denies the allegations and says that the queen respects the local tax laws and regulations. This was also confirmed to the RVD by local authorities.
https://nos.nl/artikel/2269834-rvd-maxima-houdt-zich-aan-regels-van-argentijnse-fiscus.html
Hans Jacobs of the excellent Royalblog notes that the website is very obscure and offers no proof.Its main raison d'etre seems to be to tarnish the repustation of president Macri. The accusations towards Maxima were part of a larger article in which the president was accused of tax favors for his friends. A wrong translation into Dutch made the problem seem much larger than it was, but it was nontheless repeated by several news outlets and politicians.
The website is owned by Horacio Verbitsky, a great supporter of the previous president Christina Kirchner.
The author warns that considering the great ideological differences in Argentine, the Queen's activities there -even when they are private- can become part of a political game, as seems to be the case here.
https://gpdhome.typepad.com/nieuwsb...nië-kunnen-onderdeel-worden-van-politiek.html