(a) In general. Gross income includes rentals received or accrued for the occupancy of real estate or the use of personal property. For the inclusion of rents in income for the purpose of the retirement income credit, see section 37 and the regulations thereunder. Gross income includes royalties. Royalties may be received from books, stories, plays, copyrights, trademarks, formulas, patents, and from the exploitation of natural resources, such as coal, gas, oil, copper, or timber. Payments received as a result of the transfer of patent rights may under some circumstances constitute capital gain instead of ordinary income. See section 1235 and the regulations thereunder. For special rules for certain income from natural resources, see Subchapter I (section 611 and following), Chapter 1 of the Code, and the regulations thereunder.

(b) Advance rentals; cancellation payments. Except as provided in section 467 and the regulations thereunder and except as otherwise provided by the Commissioner in published guidance (see § 601.601(d)(2) of this chapter), gross income includes advance rentals, which must be included in income for the year of receipt regardless of the period covered or the method of accounting employed by the taxpayer. An amount received by a lessor from a lessee for cancelling a lease constitutes gross income for the year in which it is received, since it is essentially a substitute for rental payments. As to amounts received by a lessee for the cancellation of a lease, see section 1241 and the regulations thereunder.

(c) Expenditures by lessee. As a general rule, if a lessee pays any of the expenses of his lessor such payments are additional rental income of the lessor. If a lessee places improvements on real estate which constitute, in whole or in part, a substitute for rent, such improvements constitute rental income to the lessor. Whether or not improvements made by a lessee result in rental income to the lessor in a particular case depends upon the intention of the parties, which may be indicated either by the terms of the lease or by the surrounding circumstances. For the exclusion from gross income of income (other than rent) derived by a lessor of real property on the termination of a lease, representing the value of such property attributable to buildings erected or other improvements made by a lessee, see section 109 and the regulations thereunder. For the exclusion from gross income of a lessor corporation of certain of its income taxes on rental income paid by a lessee corporation under a lease entered into before January 1, 1954, see section 110 and the regulations thereunder.