Basically, SEC 179 property can be fully depreciated in the first year. Residential Rental Real Estate does not qualify as SEC 179 property. Period. You can google the question yourself and find many explanations. But I only confirm to the ones on the irs.gov website.
Safe Harbor applies to those things that would otherwise qualify as a depreciable asset. Under the SH rules. Basically the rules say that some (not all) items that cost less than $2,500 can be expensed in the year they are purchased, instead of being depreciated. There are pros and cons to expensing an item that could otherwise be depreciated. The rules also have some "grey areas" where things aren't clearly identified as qualifying for SH or not.
