UPMC notes that no patient information has been lost to the thieves, who are being investigated by the Internal Revenue Service and other federal agencies.
When UPMC first confirmed the problem in February, officials believed just 22 workers had their personal information used to file bogus tax returns. The hospital network, which has 62,000 employees, later said more than 300 workers had been victimized.
The IRS says 1.2 million taxpayers were the victims of similar fraud in the 2012 fiscal year. The agency intercepted about 5 million bogus returns for the 2012 tax year.