N.Y. Comp. Codes R. & Regs. tit. 20 § 3-3.2
(Tax Law, section 208(9)(d))
Example 1: A taxpayer has a contract for the construction of a building and the subsequent installation of equipment in that building. The contract covers a period in excess of one taxable year. The taxpayer keeps its books so as to reflect the total income derived from the contract in the taxable year in which the contract is finally completed, and reports its Federal taxable income accordingly. The commissioner may require the taxpayer to report the income from the contract on the basis of the percentage of completion in each taxable year, or some other appropriate basis.
Example 2: A foreign corporation sells its New York State real estate on an installment basis, and terminates its taxable status in New York State in the year of the sale. The full profit on the sale must be included in entire net income in the year of the sale.
Example 3: A foreign corporation sells its New York State real estate on an installment basis and terminates its taxable status in New York State in a subsequent taxable year prior to the receipt of all of its installment payments. The profit included in the remaining installment payments for the sale must be included in ENI in the year it terminates its taxable status in New York State.
N.Y. Comp. Codes R. & Regs. Tit. 20 § 3-3.2