As far as I can see into it -our airplane belongs to a "big stock" company - we haver never in the last 9 years made a "private" flight as far as I can tell and I have even to report what catering for which passengers has been bought, which is deducted from the allowances of these passengers. I could be wrong, but I honestly doubt that in our case and in fact all of the aircraft around us on our home base there is a possible tax avoidance. (as they have similar schemes for the catering and whatnot) One of the I think now 12 jets on our little airfield is foreign registered, all the rest is D and for our airplane I know for sure that is was paid for from the regular account of our company. All of them are owned by German companies and none has changed ownership as far as I can tell.