- ITINs with middle digits of 78 and 79 (e.g. 9NN-78-NNNN). The IRS will send Letter 5821 to taxpayers with these expiring ITINs.
- ITINs that have not been used on a tax return for Tax Year 2013, Tax Year 2014, or Tax Year 2015
https://www.irs.gov/individuals/itin-expiration-faqs
