[ErVikingo]

In principle your "expense" must offset your profit. The "Infernal" revenue service pays a lot of attention to these types of situations just as to race horses, ...

You must run it as a legitimate business (with a profit motive) to qualify as a deduction. Having said that, your buddy's wife business should be able to take the expense as a deduction (promo expense) but your buddy would have to show an "advertising revenue" for his side of the transaction.

This is not an official opinion nor position (required disclaimer) just general background....

Do a quick search under the Racing Forum where we discussed this a bit some time ago. I have some notes on a book I planned (and never had the time) to write on the subject.