(The Hill) — The Internal Revenue Service (IRS) cannot locate thousands of microfilm cartridges containing millions of sensitive individual and business tax account records, according to a watchdog report.

The Treasury Inspector General for Tax Administration said in a report released Tuesday that the IRS cannot account for microfilm cartridges — which contain backups of tax records as required under federal law — from fiscal 2010 that were originally stored at a processing center in Fresno, Calif. 

The cartridges were meant to be among other records that were shipped to another processing center in Kansas City, Mo., last February after the California location closed.

The watchdog also found seven empty boxes, which could hold up to 168 cartridges total, at the Ogden Tax Processing Center in Utah. Ogden personnel did not know where the missing cartridges were.

More than 4,000 cartridges containing business tax account information from fiscal 2018 and 4,500 cartridges containing individual tax account information from fiscal 2019 also could not be accounted for at the Kansas City facility, according to the report.

“The personal taxpayer and tax information included on these backup cartridges is key information that can be used to commit tax refund fraud identity theft,” the report noted.

Tuesday’s report also found that the microfilm cartridges at the Ogden center are not being “adequately safeguarded to limit access” to the sensitive information they contain and that all three tax processing centers continued to store cartridges past their proper retention date.

The backup cartridges are meant to be destroyed after 30 years for individual tax records and 75 years for business tax records.