If you’re just trying to figure out the tax rate and marginal tax rate for a sole proprietorship, go here:
http://www.paycheckcity.com/calculator/netpay/us/new%20jersey/calculator.html
and plug in the profit of the business as if it was the gross pay.
Note the tax load for this individual.
That gets you the rate, except it leaves out self-employment tax.
This tells you about the joys of paying self-employment tax:
http://www.irs.gov/businesses/small/article/0,,id=98846,00.html
A super-rough calculation would be to multiply the gross income by 6.6% to calculate that.
You’re now in the ballpark of your actual tax rate.
For example, with a principal who is drawing on a gross profit of $100K:
So, I’m showing 32% based on the above. Add in 6.6% and you’re at about 38.6%.
You should ONLY take that very rough number as something to use in the very, very, very early planning stages of deciding whether or not to go into business.
To pick apart the example, by the time your gross is $100K, you should probably be in a C Corp or non-sole-proprietor apparatus, which could potentially get rid of your self-employment tax on as much as half of your gross.
Also, the calculator above, if you used it for my state, Ohio, would completely fail to notice the Commercial Activity Tax, which in some cases is 1% of your gross REVENUE, not your gross profit. That’s a massive difference.
And, for liability reasons, and liability can be massive in the land of title insurance, you really want to consider an LLC or LLP.
Short answer: get an accountant for an initial consult, even if you plan on preparing your own taxes.
That’s for ANYONE starting up a small business that will have a gross profit over maybe $1000.
Longer answer: for God’s sake, when a bank might be coming after you for a quarter million due to title defects, talk to a lawyer about whether or not you need an LLC or similar legal apparatus.