Co-ownership income allocation: each co-owner must include their computed share of house property income in total income. Where property of buildings or buildings with appurtenant land is owned by multiple persons with definite shares, each co-owner is assessed individually and must include in his total income the share of income from the property as computed under the house property provisions; the computation treats each co-owner as if individually entitled to the reliefs that adjust gross rent or annual value when determining that share.