Final answer:
A deductible casualty loss decreases the adjusted basis of property.
Step-by-step explanation:
The effect of a deductible casualty loss on the adjusted basis of property is that it decreases the adjusted basis.
When a casualty loss occurs, such as damage from a fire or natural disaster, it reduces the value of the property. This reduction in value is reflected in a decrease in the adjusted basis of the property.
For example, if a property had an adjusted basis of $200,000 and experienced a deductible casualty loss of $50,000, the new adjusted basis would be $150,000.