With more than 2 million individual taxpayer identification numbers, or ITINs, set to expire at the end of this year, the Internal Revenue Service is urging affected taxpayers to submit their renewal applications soon to beat the rush and avoid refund delays next year.

In the third year of the renewal program, the IRS has increased staffing to handle the anticipated influx of W-7 applications for renewal. This third wave of expiring ITINs is expected to affect as many as 2.7 million taxpayers. To help taxpayers, the renewal process for 2019 is beginning earlier than last year.

“Even though the April tax deadline has passed, the IRS encourages people affected by these ITIN changes to take steps as soon as possible to prepare for next year’s tax returns,” said Acting IRS Commissioner David Kautter in a news release. “Acting now to renew ITIN numbers will help taxpayers avoid delays that could affect their tax filing and refunds in 2019. The IRS appreciates the help from partner groups across the nation sharing this information with those with expiring ITIN numbers.”

ITINs that have not been used on a federal tax return at least once in the last three consecutive years will expire Dec. 31, 2018. In addition, ITINs with middle digits 73, 74, 75, 76, 77, 81 or 82 also will expire at the end of the year. These affected taxpayers who expect to file a tax return in 2019 must submit a renewal application as soon as possible.

ITINs are used by people who have tax filing or payment obligations but who are not eligible for a Social Security number.

The IRS has launched a nationwide education effort to share information with ITIN holders.

To renew an ITIN, a taxpayer must complete a Form W-7 and submit all required documentation.

For more information, visit the ITIN information page on IRS.gov.