They do not take taxes out, you are not an employee of Nike however a contracted worker, they dont tell you how to do your job, just pay you for the finished product.
They do not provided insurance either, again you are not an employee of Nike.
Salazar on the other hand would be an employee and get insurance and etc.
They make you sign an agreement not to disclose contract amounts to prevent trouble between you and other athletes, so unless it slips we will never officially know. I like the way NFL and etc show their salaries and wish we did it as well for Running.
My Guess. His base salary is around 300-500k a year, and with bonus possibilities it gets pushed to 500-850k a year. Add in prize money and appearance fees and Rupp most likely made 700k to 1.1 million this past year. He is in his prime right now so he will make this over the next few years and once he gets to the Marathon hey may push that number even higher is he becomse a 2:04 guy after running 26:20-30's and 12:40'S on the track. This is my opinion after seeing a few contracts for top tiered athletes in his very small niche. If everything goes well he will be the highest paid distance runner in the world. He won't touch Usain Bolts 10mil yearly salary and 20 million total between gatorade, puma, and etc.