When you buy real estate, you’re not just buying one asset. You’re buying land and whatever sits on it, and the IRS cares a lot about how you divide the purchase price between them.

Land doesn’t depreciate. It lasts forever in the eyes of tax law, so you can’t deduct any of it over time. Buildings and their components do depreciate. Residential rental property depreciates over 27.5 years and commercial over 39 years. The portion of your purchase price allocated to the building is the basis you’ll depreciate over those years.

This means the allocation directly affects your annual tax deductions. Allocate too much to land and you’re leaving depreciation deductions on the table every year you own the property. Allocate an indefensible amount to the building and you create audit risk.

Most investors start with the county tax assessment, which breaks out land and improvements. That’s a reasonable starting point but often not the most accurate or advantageous. An appraisal at purchase gives you a better defensible allocation. The appraiser examines the actual property and makes an informed split based on the specific land value and building condition.

A cost segregation study takes the allocation further. Instead of treating the building as a single asset, cost segregation identifies components that qualify for shorter depreciation lives. Personal property like appliances or carpeting might depreciate over 5 or 7 years. Land improvements like parking lots or landscaping might depreciate over 15 years. Accelerating depreciation on these components through tax advisory and planning puts more deductions in the early years of ownership.

The allocation you establish at purchase becomes part of your permanent records. Your depreciation schedules flow from it. When you eventually sell, your gain or loss calculation uses these same numbers. If you do a 1031 exchange, the basis carries over to the replacement property. Get the allocation wrong at the start and the error compounds through every year of ownership and into the eventual sale.

This is one reason getting your books set up correctly from day one matters. A real estate accounting firm that understands depreciation will track your original allocation, maintain accurate schedules, and ensure the numbers tie back to your tax returns year after year. The allocation isn’t just a number you pick once and forget. It’s the foundation for every depreciation deduction you’ll take and the basis you’ll use when you eventually exit the investment.