Final answer:
Depreciation allowed refers to the actual deduction taken, while depreciation allowable refers to the maximum deduction allowed. Both reduce the adjusted basis of the property.
Step-by-step explanation:
The difference between depreciation allowed and depreciation allowable is that allowed refers to the actual deduction taken, while allowable refers to the maximum deduction allowed by tax laws.
Both depreciation allowed and depreciation allowable result in a decrease in the adjusted basis of the property. The adjusted basis is the original cost of the property minus the depreciation deductions taken.
For example, if a property is purchased for $100,000 and the depreciation allowed in a given year is $5,000, the adjusted basis would decrease to $95,000. If the depreciation allowable for that year is $10,000, but only $5,000 is taken as a deduction, the adjusted basis would also decrease to $95,000.