Deductions & credits

In TurboTax you should post the Personal Information, including the children to his tax return.  This will give him a filling status of Head of Household, thus dead-beat spouse out of the picture.

You will have to get the Self-Employment software.  You can get it online at TurboTax.Intuit.com.

If you received a 1099-NEC, you will be considered Self-Employed and be assessed both income tax and self-employment taxes.  The expenses you enter will reduce both taxes. They will be entered on Schedule C described a little later.

Self-employment taxes an additional 15.3%. The rate consists of two parts: 12.4% for social security (old-age, survivors, and disability insurance) and 2.9% for Medicare (hospital insurance).

On the sidebar 

1. Select Federal 
2. Wages & Income 
3. Select Wages and Salaries, or Revisit 
4. Scroll to Other Common Income
   1. Refunds Received for State/Local Tax Returns
   2. Form 1099-NEC
   3. Form 1099-MISC
   4. Form 1099-K
5. Verify that you do have a 1099-NEC [Yes]
6. You may have to upgrade your software.
7. The next screen is to [Add a 1099-NEC]
8. Enter your information.

To prepare your Schedule C,

1. Log into TurboTax.
2. Select Income & Expenses.
3. Work on other income
4. Scroll down and select Self-employment income and expenses
5. Continue through the interview.

If this does not completely answer your question, please include @JohnB5677 in your reply and provide some additional details.