INDIANAPOLIS -- Thousands of retired state and local government workers were shocked on Friday when they discovered that their monthly pension checks were substantially reduced.

Workers were especially unhappy that they got no advance warning they would be receiving less money, 6News' Norman Cox reported.

The Public Employees Retirement Fund said the shortage happened because one of the tax cuts in the federal stimulus package expired. A notification sent to retirees didn't get to them until after payments had arrived.

Pat Zerbo, of Fishers, said she checked her checking account online on Friday, as she does every month on payday, but was dismayed that the deposit was $48.75 less than the previous month.

"We didn't know, so we called PERF," Zerbo said, but she added that the explanation she received was confusing.

Zerbo said she was told that she received less money because Congress didn't renew one of the tax cuts passed during the term of President George W. Bush, but she called 6News in hopes of getting the correct answer.

One of the elements in the stimulus package passed under President Barack Obama expired, which raised retirees' federal income tax withholding.

"Basically, the Make Work Pay tax credit that was adopted by the federal government last year expired at the end of the year, and for some folks, that resulted in an increase in the amount of taxes withheld," said Jeff Hutson, PERF spokesman.

Normally, retirees such as Zerbo who have direct deposit don't get monthly statements unless the amount changes. Because it changed this month, a notice was sent, but it arrived late.

"Even when it did come out, it was just a short sentence that didn't really explain anything," Zerbo said.

"A lot of people get their checks on Friday on direct deposit. This came out in the mail on Saturday," Hutson said. "I think it would have been a very good idea to have had it to people a little sooner than that. We certainly had a lot of business in our call center on Friday."

For most working people, the expiration of the tax break is made up by the cut in the Social Security withholding tax. Because retirees don't pay Social Security, they've lost money because of the expiration.