How do I calculate how much I have to pay next year? I am a independent contractor in the home health care industry

TurboTax (TT) can prepare the quarterly payment vouchers. In your 2019 software, enter at:

Federal Taxes or Personal (H&B version)

-Other Tax Situations

  -Other Tax Forms

    -Form W-4 and Estimated Taxes - Click the Start or Update button

On the next screen answer No to the W-4 question

You should make estimated tax payments for the current tax year if both of the following apply:
- 1. You expect to owe at least $1,000 in tax for the current tax year, after subtracting your withholding and credits. 
- 2. You expect your withholding and credits to be less than the smaller of: 90% of the tax to be shown on your current year’s tax return, or  100% of the tax shown on your prior year’s tax return. (Your prior year tax return must cover all 12 months.)

If your goal is just to avoid the underpayment penalty, then paying 100% of the prior year tax liability is the “safe haven”

Or you can obtain  blank IRS Form 1040-ES from the IRS. The form and instructions are at this link:  https://www.irs.gov/pub/irs-pdf/f1040es.pdf

You can also pay Federal directly here.  Be sure to select 1040ES:

https://www.irs.gov/Payments