I assume from the way you've phrased your question and the information you've provided that you are being paid an an "independent contractor", that is you are not receiving a true "paycheck" showing gross wages, amount withheld for taxes, etc. I also assume you perform this service in the U.S.
If I've got all that right then you have the right product - TurboTax Home & Business - and you will put your revenue, along with any expenses incurred in the performance of your service - on Schedule C. The "bottom line" of Schedule C will flow to line 12 of your Form 1040 (Business income) to be taxed at ordinary income rates. You'll also be assessed "Self employment tax", (Social Security and Medicare), at roughly 15%, but you'll get an above the line deduction for one-half the self employment tax on the face of Form 1040.
You "file" your income tax return annually, exactly like any wage earner; that income tax return is generally due April 15 of the following year. However, you'll need to pay income taxes, (estimated taxes), on a quarterly basis if this income, which is not subject to withholding, is significant and if you don't have taxes withheld somewhere else, e.g., your W-2 job.
There's no way to know "what percentage" you should be saving in order to pay those quarterly estimated taxes since that depends largely on your personal situation, which no one here knows. Since you know your income will be taxed at least at 15%, (SE Tax), that's the bare minimum, but it goes up from there based on your tax bracket. Don't forget that you have to pay state estimated taxes too, if you live in a state with an income tax.
When you prepare your 2016 income tax return be sure to work through the "W-4 and estimated taxes" interview under the "Other tax situations" tab. That interview will assist you in estimating how much, if any, estimated taxes you should be paying and it will print out the required forms to do so.
Tom Young
