Affiliate commission and tax

Hi,

This might sound like a pretty basic question but I'm going to ask it anyway...;-)

As an affiliate *merchant* that pays my affiliates the agreed commission, come tax time I assume that I can class all of these commission payments as a business expense?

Further to this, I am considering taking complete control and managing my affiliate program "in-house" rather than use the services of something like ClickBank...

...if I were to ever use ClickBank though, lets say that I sell a product for $50 and offer 50% commission ($25), where do I stand in terms of being able to claim commission paid as an expense? My guess is that I can't, as when you sell something through ClickBank, technically hasn't ClickBank already first brought my product from me?

Regards,
Adam