"If a trustee incurs expenses then he or she should be entitled...

"If a trustee incurs expenses then he or she should be entitled to a reimbursement as long as such expenses were necessary and reasonable."

The problem with this statement, is that evil doers would be testing the limits of reasonable constantly.

The tax man will disagree with your definition of service.

As far as the sole purpose test goes, it could be argued that the non-super trust might gain a benefit by being able to spread some of its fixed costs across the 2 entities. That would be enough to trigger the tax man's ire.

Unreasonable, in your case probably, but remember, you are paying for the potential crimes of those that wish to do bad things.

More efficient to have a blanket ban.

Hence, separate entity for corporate trustee of super fund, and they are billed directly for the super funds costs, without contamination from anyone else.

Another factor to consider, even if you were right, any sum actually worth worrying about, risks precipitating a full audit by the ato.

And they go thru everything[ personal, super, company, trust, spouse], and it is time consuming , and expensive , even if everything is perfect!

cheers