I asked why he's an s-corp vs. filing a Schedule C.

You save a bit on self-employment taxes by using an S corp rather than using Schedule C.

When you have an S corp, you're only paying self-employment taxes on the amount that you take as wages. (Of course, in a wage context, it's not called "self-employment taxes"; it's called "Social Security withholding" and "Medicare withholding"; but it's essentially the same thing).

When you report income on Schedule C, it's all subject to self-employment taxes.

Let's take an example. John Doe is an independent contractor who has profit of $100,000 in a given tax year. If he reports his entire income on Schedule C, he will pay $15,000 in self-employment taxes.

Now let's say that instead of reporting on Schedule C, John Doe set up an S corp and took $40,000 as salary and $60,000 as a distribution. Only the $40,000 would be subject to Social Security and Medicare withholding, so he would only be paying $40,000 x 15% = $6,000 for the equivalent of self-employment taxes by using an S corp.

$15,000 - $6,000 = $9,000 tax savings simply by using an S corp. Sure, there are other complexities, such as the increased administrative costs of setting up an S corp (e.g., payroll), having to pay a CPA for another tax filing, the fact that on your 1040 you can deduct 50% of self-employment taxes paid, various state complexities, etc., but the fact remains at the end of the day that at a certain level of income, a self-employed person / independent contractor will save some money by using an S corp rather than reporting on Schedule C.