How do I adjust the amount on line 4a of Form 8960?

To adjust the amount on line 4a of Form 8960 Net Investment Income Tax, go to:

1. Federal Section
2. Other Taxes
3. Form 8960 - Net Investment Income Tax
4. Adjust Net Income or Loss for Non-section 1140 trade or business (line 4b). 

Line 4a is the rental real estate, royalty, partnership, S corporations, trust income subject to Net Investment Income Tax.