Individual Taxpayer Identification Numbers will expire if not used on a federal income tax return for any year during a period of five consecutive years, the Internal Revenue Service announced today. That is, the IRS will not deactivate an ITIN that has been used on at least one tax return in the past five years. To give all interested parties time to adjust and allow the IRS to reprogram its systems, the IRS will not begin deactivating ITINs until 2016. Further details here.