Generally, to find the basis for depreciation:
- Multiply the cost or other basis of the property by the percentage of business/investment use.
- Subtract any section 179 expense deduction.
- Subtract any special depreciation allowance (50% and 30%).
For additional information, please refer to IRS Instructions for Form 4562 Depreciation and Amortization (Including Information on Listed Property) and IRS Publication 946 How to Depreciate Property.
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