These proposed regulations provide guidance under section 451 regarding the  taxable year of inclusion of revenue that has been deferred from inclusion in gross income under section 1.451-5 of the Income Tax Regulations. If a taxpayer has deferred revenue from gross income inclusion under section 1.451-5, and a controlling interest of its stock is acquired by an unrelated corporation that writes down any part of the deferred revenue for financial purposes, the taxpayer must include in gross income the amount of the deferred revenue that is written down in the year of the write-down.