Tax is a strange thing to deal with. What's the most important thing that incorporated startups in the US should know about tax?
That if you don't pay it, you go to jail.
My father was fond of saying you need
three things in life. A good doctor, a
forgiving priest, and a clever
accountant. The first two, I've never
had much use for them. But the third -
(he raises his glass to recognize
Stern).
-- Oscar Schindler in the movie
That's a very big question. Here are some tips.
First, new companies often owe a minimum amount of tax depending on which state they are in even if they do not make any money. For example, in California, that amount is $800 per year. This can be a lot for a new company who is just starting out.
Next, depending on which state you are in, the type of entity you choose, such as C Corporation, S Corporation, or LLC will have an impact on how your taxes are paid and how much tax you will pay.
Lastly, if you are an officer of a company, you'll need to pay payroll taxes which have to be paid quarterly to the IRS, so an accountant may be necessary depending on the size of your company.