The state says it may have mistakenly made $28M in payments, but won't say exactly how many people are affected.
One person who owes $2,700 shared the letter from the Employment Security Commission with ABC11 Eyewitness News.
The letter states, "Should it become necessary, the overpayment may be collected by civil action and the cost of such action added to the overpayment."
However, the ESC isn't calling it payback but a reduction in benefits for some for at least a week.
ESC official David Clegg admits it was a mistake on the commission's part, blaming the bad math on a system and staff unaccustomed to recipients receiving benefits for up to two years.
Those who have received a letter may receive another one. Some benefit recipients have until October 8 to file a waiver.