Requirement to subtract personal usage days from property rental? Depends
The return’s schedule E itself reports actual rental days at fair rental value and the number of days of personal use*. Actual rental days will include only just that – actual rental days.
The expense allocation** is made based on days-available-for-rent-actually-rented and personal days not rented even if available for rent.
Items measured alone by “available to rent” regardless of actual rental (so, no personal days are deducted if the property was available to rent then) are: claiming depreciation expense (used in your rental activity even if it is temporarily idle) & claiming ordinary and necessary rental expenses (see below and note that if the property is not held out and available for rent while listed for sale, such latter expenses are no longer deductible).
*For each property, report the number of days in the year each property was rented at fair rental value and the number of days of personal use. A day of personal use is any day, or part of a day, that the unit was used by:
You for personal purposes,
Any other person for personal purposes, if that person owns part of the unit,
Anyone in your family (or in the family of someone else who owns part of the unit), unless the unit is rented at a fair rental price to that person as his or her main home,
Anyone who pays less than a fair rental price for the unit, or
Anyone under an agreement that lets you use some other unit.
** You can deduct your ordinary and necessary expenses for managing, conserving, or maintaining rental property from the time you make it available for rent.
If you use a dwelling unit for both rental and personal purposes, divide your expenses between the rental use and the personal use based on the number of days used for each purpose. When dividing such expenses, any day that the unit is rented at a fair rental price is a day of rental use even if you used the unit for personal purposes that day. (This rule does not apply when determining whether you used the unit as a home). Any day that the unit is available for rent but not actually rented is not a day of rental use.