(Salem, OR) -- A mistake by the Oregon Employment Department means up to 12-thousand people who received unemployment last year might need to file updated tax forms. The problem happened during the switch from the old computer system to Frances Online. Incorrect 1099-G forms were sent to some people who received unemployment benefits last year. The department is going through a process to identify all errors, validate tax forms and contact affected customers. The Oregon Employment Department has details on its website.