Taxpayers with individual taxpayer identification numbers should find out if their number expires this year. If it does, they should renew it now to avoid delays with their refund when they file their taxes next year.

An ITIN is a tax ID number used by taxpayers who don’t qualify for a Social Security number. Here’s what these taxpayers need to know about which numbers are expiring and how to renew them.

Which numbers are expiring at the end of this year?

Any ITIN with middle digits 83, 84, 85, 86 or 87.

Any ITIN not used on a tax return in the past three years.

What about numbers that expired in the last few years?

ITINs with middle digits 70 through 82 that expired in 2016, 2017 or 2018 can also be renewed.

How does someone renew their number?

Taxpayers with expiring ITINs need to complete renewal application, Form W-7, Application for IRS Individual Taxpayer Identification Number. They should include all required ID and residency documents. Failure to do so will delay processing. until the IRS receives these documents.

When should someone submit their renewal applications?

As soon as possible. With nearly 2 million taxpayer households affected, applying now will help avoid the rush.

What are some tips to avoid common mistakes that are made when submitting their renewal?

• Indicate the reason for the ITIN on the Form W-7.
• Mail the proper identification documents. Taxpayers mailing their ITIN renewal applications must include original identification documents or copies certified by the issuing agency and any other required attachments.
• Include all supporting documentation, such as U.S. residency or official documentation to support name changes.
• Complete the new W-7 application.