Pension recipients are being asked to pay back pension overpayments that in some cases reach tens of thousands of dollars.

Almost 600 retired metal workers belonging to the Sheet Metal Workers Union No. 73  have been notified that their pension fund incorrectly paid out more than $5 million in overpayments and that the fund wants its money back plus interest.

One member, Carole Grant, 75, told CNN Money that the sheet metal worker’s plan claims she owes $61,000 on overpayments spanning back 20 years.

“I don’t feel that I should be penalized for the mistakes that they made,” Grant told CNN Money.

Others are experiencing similarly hefty recoupments. The American Water Works Co.’s pension told Carol Montague, 67, she owes nearly $45,000 for over five years of overpayments. Montague says she made a mistake in not verifying that her payments were made in the correct amount but says she assumed they were accurate.

“I put it away in a steel box. I never looked at it again. It was stupid on my part. But it took (almost) six years for them to find out they overpaid me?”

The recoupment trend has increased as funds nationwide face tighter economic constraints.