Individuals, including sole proprietors, partners, and S corporation shareholders, can generally use Form 1040-ES to calculate estimated taxes.

But before calculating your estimated tax, you must know your expected adjusted gross income, taxable income, taxes, deductions, and credits for the year.

As a calculation, if you expect this amount to be zero, then enter zero in the box, but make sure your estimate is as accurate as you can with the information you have. 

If the IRS later finds that the estimate wasn’t reasonable, the extension will be null and void.