nonpassive loss from grantor letter

Since it is non-passive business income, it is probably from an interest in a normal business. Such income would normally be reported on a Form 1099-NEC if you were a material participant in the business, or a Form 1099-MISC if you had a passive interest in the business. If you don't have those forms, you can enter the income in the self-employed income section of TurboTax if you materially participate in the business. Otherwise, you can enter it as "other income" as follows:

1. From the Federal menu in TurboTax find Wages and Income 

2. Find Less Common Income

3. Choose Miscellaneous Income, 1099-A, 1099-C

4. Choose Other Reportable Income

5. Enter a description of the income and enter the amount