Over the last two weeks, some Maryland senior citizens received letters from the state comptroller's office saying that they owe more taxes than they paid.
The mistake, which was discovered by volunteer tax preparers at the Pascal Senior Center, affected 1,800 people.
"I didn't know what was going on at first," said tax volunteer Dan Graham.
Most of the letters went to Baltimore-area residents, but some went to the D.C. area as well. Graham said he saw requests for between $900 and $2,200 in back taxes.
Harold Wicker of Edgewater, Md., has been retired and living off his savings for 12 years.
When Wicker received a letter from the comptroller's office that said he owed $1,300 in back taxes, he said it scared him.
"It hurts my savings. I don't have much of a savings, but I like to keep what I got!" he said.
Each letter alleges that its recipient claimed pension exclusions they weren't entitled to on their 2008 tax returns.
The comptroller's office said this happened due to faulty data it received from the IRS. Meanwhile, follow-up letters clarifying the error have been sent to all 1,800 letter recipients.