26 CFR § 1.167(a)-6 - Depreciation in special cases.
(a) Depreciation of patents or copyrights. The cost or other basis of a patent or copyright shall be depreciated over its remaining useful life. Its cost to the patentee includes the various Government fees, cost of drawings, models, attorneys' fees, and similar expenditures. For rules applicable to research and experimental expenditures, see sections 174 and 1016 and the regulations thereunder. If a patent or copyright becomes valueless in any year before its expiration the unrecovered cost or other basis may be deducted in that year. See § 1.167(a)-14(c)(4) for depreciation of a separately acquired interest in a patent or copyright described in section 167(f)(2) acquired after January 25, 2000. See § 1.197-2 for amortization of interests in patents and copyrights that constitute amortizable section 197 intangibles.
(b) Depreciation in case of farmers. A reasonable allowance for depreciation may be claimed on farm buildings (except a dwelling occupied by the owner), farm machinery, and other physical property but not including land. Livestock acquired for work, breeding, or dairy purposes may be depreciated unless included in an inventory used to determine profits in accordance with section 61 and the regulations thereunder. Such depreciation should be determined with reference to the cost or other basis, salvage value, and the estimated useful life of the livestock. See also section 162 and the regulations thereunder relating to trade or business expenses, section 165 and the regulations thereunder relating to losses of farmers, and section 175 and the regulations thereunder relating to soil or water conservation expenditures.