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I realize your dilemma. You don't want to do your own taxes.
The easiest way to handle this is to find an H&R Block tax store - they'll give a free hour's time in discussing what to do about your taxes - you'll feel MUCH better about it then.
Simple method: Open a business checking and savings. Take 30-percent of your income and stash it in the savings - plan on using it for paying taxes at the end of the year. Note: as a sole proprietor, you don't have to pay your income tax until end of year. When/if you get employees, that's a different matter.
In this case, I think we're talking about a start up company, we have to assume that "net" is zero or close to it. Its easy to rack up huge expense write-offs in those first years. The IRS "fine" for not paying quarterly taxes is zero if you netted zero.
But if you're turning a profit your first year out, then yes you will have to pay quarterly - but that won't be determined until after the first year when you file your taxes - in other words; you won't pay taxes until the end of the year.
(a little off topic now. . .)
Not only can you have lots of tax-deductible material goodies, you can actually reduce the family's total taxable income if your losses are structured properly (assuming you have a working spouse).
The W9 and tax filing issues are pretty simple.
But if you know how to structure your expenses properly you shouldn't have to pay any tax in the startup year.
That is why my recommendation to seek professional tax council is most important. (especially when you can get it free)