• Taxpayers whose ITIN is expiring and who expect to have a filing requirement in 2020 must submit a renewal application. Others do not need to take any action. ITINs with the middle digits 83, 84, 85 or 86, 87 (For example: 9NN-83-NNNN) need to be renewed even if the taxpayer has used it in the last three years. The IRS will begin sending the CP48 Notice, You must renew your Individual Taxpayer Identification Number (ITIN) to file your U.S. tax return, in early summer to affected taxpayers. The notice explains the steps to take to renew the ITIN if it will be included on a U.S. tax return filed in 2020. Taxpayers who receive the notice after acting to renew their ITIN do not need to take further action unless another family member is affected.
• ITINs with middle digits of 70 through 82 have previously expired. Taxpayers with these ITINs can still renew at any time, if they have not renewed already.

To renew an ITIN, a taxpayer must complete a Form W-7 and submit all required documentation. Taxpayers submitting a Form W-7 to renew their ITIN are not required to attach a federal tax return. However, taxpayers must still note a reason for needing an ITIN on the Form W-7. See the Form W-7 instructions  for detailed information.

Spouses and dependents residing outside of the U.S. only need to renew their ITIN if filing an individual tax return, or if they qualify for an allowable tax benefit (e.g., a dependent parent who qualifies the primary taxpayer to claim head of household filing status.) In these instances, a federal return must be attached to the Form W-7 renewal application.

• Mail the form, along with original identification documents or copies certified by the agency that issued them, to the IRS address listed on the Form W-7 instructions. The IRS will review the identification documents and return them within 60 days.
• Work with Certified Acceptance Agents (CAAs) authorized by the IRS to help taxpayers apply for an ITIN. CAAs can authenticate all identification documents for primary and secondary taxpayers, verify that an ITIN application is correct before submitting it to the IRS for processing and authenticate the passports and birth certificates for dependents. This saves taxpayers from mailing original documents to the IRS.
• In advance, call and make an appointment at a designated IRS Taxpayer Assistance Center to have each applicant’s identity authenticated in person instead of mailing original identification documents to the IRS. Each family member applying for an ITIN or renewal must be present at the appointment and must have a completed Form W-7 and required identification documents.

Reference: https://www.irs.gov/newsroom/millions-more-itins-set-to-expire-in-2019-irs-says-renew-early-to-prevent-refund-delays