Someone asked this question last week on a similar thread; the answer I gave there is still relevant so I'm just going to copy and paste it here:
Compounding investment returns. If I loan you $1000 at 5% interest, I have to report $50/year of interest income on my tax return. Since I pay approximately 40% income tax (federal + provincial), I have an after-tax return of 3% compounding annually. If you abolish corporate income taxes, then I could have my company loan you the $1000 and receive the interest; it would then compound at 5% per year, and I would only pay income tax when the money is paid out to me as a dividend. In effect, you would be turning corporations into tax shelters.
Now, this isn't absolutely insurmountable; in fact, Canada already has different tax rates for "active business income" vs. investment income, and theoretically you could have a 0% rate on "active business income" and a 40% corporate tax rate on investment income (which would then create non-taxable dividends when finally paid out to individuals). But you'd still have the complication that "retain profits" produces a different taxation result than "pay out profits as dividends, then raise more funding a few years later".
Can you explain what the problem is? I mean you use the term "tax-shelter" and we associate that with something bad. But what's wrong with only taxing when you actually get access to the money you made?
You can't even sell the company without having to pay taxes. The money seems 100% unusable till you pay taxes on it. I guess you can reinvest it into something else without cashing out, but that hardly seems like a bad thing
Well, the most obvious problem is that rich people (who can afford to leave their money invested for longer) pay less tax.
But I see your point: Though it would seem that the way people currently get paid with stock options - where you pay tax when you "cash out" - is effectively equivalent (except it's even more regressive because the capital gains tax is a joke).
But as with anything, there are pros and cons to S Corp vs C Corp vs LLC.
Here's the first hit on google: http://www.forbes.com/sites/robertwood/2012/05/03/c-or-s-cor...
Corporations are participants of the economy and their profits depend on tax-financed public goods: healthy and educated workforces; good infrastructure; publicly enforced respect for contracts and property rights, and so on. When corporations avoid or evade tax, legally or illegally, they free ride on the backs of the rest of us. Stop taxing them, and you savagely undermine political community.
[1] eg: http://www.watchcollectinglifestyle.com/home/sihh-2014-van-c...