Insurance Company Tax Modernization and Parity Act of 2017 This bill amends the Internal Revenue Code to allow affiliated life and non-life insurance companies to file consolidated tax returns. The bill also allows: (1) a phase-in of the full application of losses of affiliated non-life insurance companies against the taxable income of an affiliated life insurance company for taxable years beginning after December 31, 2017, and before January 1, 2024, and (2) an automatic waiver of the five-year waiting period applicable to affiliated non-life insurance companies for offset of their losses against life insurance company income.