On rental property your annual depreciation write off is 3.636%, on commercial property it's 2.564%. Since rental property is 27.5 year, 1/27.5 = 3.636% and on commercial its 39 year, 1/39 = 2.564%. So in that $100K rental property with $75K building your depreciation write off would actually be $2727. That brings your taxable income down to $1273. You could stop there or you could maximize depreciation with cost segregation.
Cost seg breaks down the building into building components and personal property with rental property building components depreciating over 27.5 years straight line and personal property depreciating over 5, 7 or 15 years with 200% or 150% declining balance.
In the $100K example if 10% was reallocated to 5 year property through cost seg that's $7.5K depreciated over 5 years and $67.5K depreciated over 27.5 years. The 5 year property gets 200% declining balance depreciation so thats 40% depreciation in the first year declining after. So that's a $3000 depreciation write off in the first year declining after for the $7.5K personal property and a $2454 depreciation write off for the $67.5K building components. This shows your taxable income at a loss of $1454 in that first year, a loss of $254 in the second year, an income of $466 in the third year, and so on until year 5 when the personal property is fully depreciated and you continue depreciating the building components at $2454 per year giving you a taxable income of $1546 in years 6-27.5 of ownership.
It's a little complex as to be applied properly the study must be done by a construction engineer trained in cost seg and applying the hundreds of pages of tax code pertaining to depreciation. The great thing about cost seg is it allows you to catch up on prior year depreciation deductions that you missed so if you do cost seg 5 years after purchasing that $100K property you would have already had 5 years of $2727 depreciation deductions which would be converted into $2454 depreciation deduction for the building components and catch up depreciation of $6137 on the personal property to fully depreciate it since you already took $1363. That would give you a loss on taxable income of $4591 in that year and then go to $1546 taxable income as shown above. Going from a taxable income of $1237 to a loss of $4591 would be an income reduction of $5828 resulting in $2039 in tax savings in the current year assuming a 35% tax rate ($2307 at 39.6%).
This is a small example, but these numbers scale up and generally become more favorable with larger properties over $500K. Just to be clear cost seg does not create more depreciation, rather it front loads a portion of the depreciation resulting in a much larger deduction now with a decreased deduction later. In the example above there are much larger depreciation deductions in the first 5 years, with a slightly lower deduction in years 6-27.5 - $2727 entire building 27.5 year straight line vs $2454 building components 27.5 year straight line: a $246 annual depreciation reduction or about 9% less in later years.
How's that for a cash flow increase? Of course because of the engineering work and on site survey involved the cost of a study is high, but the tax benefits of accelerated depreciation far outweigh the cost of the study for most properties. Investors must also consider depreciation recapture upon sale of the property. If you are trading up when you sell you could use a 1031 exchange and avoid recapture altogether.