Page 3 of the original 1913 income tax return provides for depreciation deduction as follows:
Amount representing a reasonable allowance for the exhaustion, wear, and tear of property arising out of its use or employment in the business, not to exceed, in the case of mines, 5 per cent of the gross value at the mine of the output for the year for which the computation is made, but no deduction shall be made for any amount of expense of restoring property or making good the exhaustion thereof, for which an allowance is or has been made
Instead of deducting the full cost of the cost of real estate, an investor is required to only write off a portion of his initial investment over time.