More details would give some perspective. Use of what? For whose business? What entity's tax return is this (which form)? Who owns whatever it is that got rented? What is the other portion used for?
"Level Up" is a gaming function, not a real life function.
At the bottom of Screen 18 in Other Information you have two options:
1. Percentage of Ownership If Not 100 Percent (.xxxx)
|General Information||Screen 18; Code 500|
Enter in .xxxx format the percentage of ownership, if less than 100% (e.g., enter 75% as .75). The program limits rents, royalties, and all expenses based on the percentage entered. The program reduces the net profit or loss on Schedule E, Part I.
Note: When you enter depreciation related to this activity on Screen 22, Depreciation and send it to Schedule E, enter the percentage of ownership in this field and do not enter "Percentage of Business Use" (Screen 22, code 503).
2. Percentage of Tenant Occupancy If Not 100 Percent (.xxxx)
|General Information||Screen 18; Code 503|
Enter the percentage of occupancy, in .xxxx format, if not 100% (e.g., enter 75% as .75). This entry causes the program to allow the full amount from "Rents Received" (Screen 18, code 2) and to limit indirect expenses to the percentage entered. The program carries the disallowed portion of indirect "Interest: Mortgage-Banks, etc." and "Taxes: Real Estate" (Screen 18, codes 209 and 213) to Schedule A.
Note: The program applies the percentage entered to all indirect expense items except depreciation. If you enter depreciation related to this activity on Screen 22, Depreciation and send it to Schedule E, you must enter the percentage related to the owner occupancy in "Percentage of Business Use" (Screen 22, code 503).
It depends. If you own less than 100%, enter it toward the bottom of Screen 18 , Other Information, Percent of ownership if not 100%.
If it's a vacation rental-enter in the middle of that screen in Personal Use of Dwelling Unit (Including Vacation Home), although I think it's better to enter days and let the software calculate.
EDIT: I didn't see George's more detailed answer when I posted mine.