ITINs are tax processing numbers that are issued to foreign nationals and others who do not qualify for Social Security numbers but have federal tax filing or reporting requirements. This includes some non-resident aliens, and dependents or spouses of U.S. resident aliens or non-resident alien visa holders.

ITINs that the taxpayer has not used on a federal tax return in the past three years are no longer valid unless the taxpayer takes action to renew the ITIN. In addition, ITINs issued before 2013 must be renewed, even if such numbers have been used in the past three years.

Taxpayers who need to renew their ITIN but fail to do so before filing a tax return may not be eligible for certain tax credits, such as the American Opportunity Tax Credit and the Child Tax Credit, until the taxpayer renews the ITIN. In addition, failure to renew an expired ITIN may cause a refund delay. ITINs only need to be renewed if the taxpayer has to file a federal tax return.

The changes in ITIN requirements were necessitated by the Protecting Americans from Tax Hikes (PATH) Act, which Congress passed in December, 2015.