Just found what I was looking for. IRS publication 527 at https://www.irs.gov/pub/irs-pdf/p527.pdf on page 4, third column under the heading "Vacant while listed for sale"
If you sell property you held for rental purposes, you can deduct the ordinary and necessary expenses
for managing, conserving, or maintaining the property until it is sold. If the property isn’t held out and available for rent while listed for sale, the expenses aren’t deductible rental expenses
At this point, unless I find something that states otherwise, I would appear to me expenses incurred while the property is listed for sale are carrying expenses. However, expenses incurred from the time the last renter moved out, until it was actually listed would not be. (most, if not all would be part of the improvement costs).
