Quote from FuturesTrader71:
Consult an accountant, but this is what I understand (this may only apply to LLC's and corp).
You don't have to pay any tax in the first year. By April 15th of the second year, you will have to pay your taxes on all of the first year's gains PLUS a quarterly installment for the second year. As long as you pay 110% of the tax you paid on year 1 for the second year, then you will be fine.
For example, if you made $100,000 in 2005, you will owe tax on that amount minus your deductions come April 15th, 2006. Let's say that liability is $30,000. So on April 15th, 2006, you will pay $30,000 for 2005 PLUS $8,250 for the first quarter of 2006. The $8,250 is $30k x 110% divided by 4. You will pay this $8,250 every quarter.
The 110% is to avoid the penalty for not paying enough in case you make more. If you feel that you don't have the discipline to put away the money for tax day, then you should pay into your taxes an amount equal to 40% of that quarter's earnings. You will then get money back once you file.
I hope that helps.