What does RE depreciation apply to?

[Jonah Stiles]

So my father is looking to buy a rental property. Potential NOI totals to about $40,000 a year although the ROI isn't marginally positive so he would almost have a 0% return on investment. He will be retiring in the next couple years and will no longer have an income.

My question is would he be able to take advantage of the depreciation of the property without a disposable income? Must he have a disposable income in order to take advantage of depreciation, or is it possible for him to apply this to the NOI of the property. And if so how would that work?