I am asking this question as a true sole proprietor that has no other income from a second job or previous employer. As I understand it FICA taxes is an easier way to refer to your Social Security Tax and Medicare Tax in one. I also know that I can, and should, make estimated tax payments towards this throughout the year through EFTPS.
Is FICA all I need to worry about as a sole proprietor? Meaning, when I fill my 1040 for the year is this what I am paying taxes for; minus any individual State taxes I might be required to pay.
Do I pay FICA and Federal Taxes on my income? Is FICA really my Federal Taxes in this case? I think I am mixing up my terminology here.
Other people who find this post may benefit if you can cover this question as well:
Does any of this process or information change if I work as a sole proprietor and have a second job with an employer?
UPDATE - Clarifying question & answer for future users
As a sole proprietor with no other income you need to pay taxes on FICA (Social Security and Medicare) plus Federal Income Tax. So you should always depending on your tax bracket and not accounting for State Taxes withhold a percentage of your income to insure you always pay the correct amount of taxes including any unforeseen taxes; like crossing the threshold into a higher tax bracket. This is why briantist's answer mentions 35% for his personal circumstances and why for me this currently is about 15% - 20%. Your mileage (amount you withhold) may vary.