The error means 720 people's T5 tax forms — which report social assistance income — were sent to their former trustees, the Community and Social Services Ministry said in a statement.
The problem affected 0.1 per cent of people who are receiving social assistance T5s. The ministry said it has informed the Information and Privacy Commissioner and has sent letters to those affected by the T5 problem as well as the former trustees, requesting they return the T5s sent to them in error.
The mishap occurred when the T5 system pulled old data from the $240-million Social Assistance Management System, the ministry said. SAMS has been plagued with problems since its rollout late last year, but the ministry said this error was not caused by SAMS itself.
SAMS erroneously queued up $20 million in welfare and disability support overpayments in December. The Ontario Public Service Employees Union, which represents caseworkers, and the opposition parties say others who depend on social assistance got far less than normal or didn't get any payment at all.
New Democrat Cindy Forster said someone should lose their job for breaching the privacy of hundreds of people.
"Now we have a privacy issue for 700 of the most vulnerable people in this province," she said. "These are people that do not have the legal means to even address that their privacy has been breached."
The social assistance director sent a memo to administrators saying the error happened in cases where clients had multiple cases in SAMS. About half of the T5s were sent to community agencies, approximately another half were sent to individuals acting as trustees and a small amount were sent to Ontario Works offices.
"The Ministry of Community and Social Services takes every effort to ensure the privacy and confidentiality of all information within our custody," Jeff Bowen wrote. "We have made necessary changes for future T5s and are reviewing our procedures to ensure this situation will not reoccur and continue to increase system testing and validation."
The ministry also announced it has selected PricewaterhouseCoopers as an independent adviser to help with SAMS.
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