Depreciation is an accounting method that expenses the acquisition cost of fixed assets like buildings over their legal useful life. In real estate investment, recording building depreciation as an expense provides income tax savings.

For used properties, if the building age exceeds the legal useful life, use 'useful life x 0.2'. If not exceeded, use '(useful life - age) + age x 0.2'. Round down fractions, minimum 1 year.

No, land is not subject to depreciation. Only the building portion can be depreciated. Therefore, it's important to verify the land-building price allocation in the sale contract and set the building ratio correctly.