WASHINGTON (November 16, 2009)--More than 15 million taxpayers could discover unexpectedly that they owe taxes when they file their federal returns next spring because the government was too generous with the new Making Work Pay tax credit.

The Treasury Department's inspector general for tax administration issued a report Monday that says taxpayers are at risk if they have more than one job, are married and both spouses work, or receive Social Security benefits while also earning taxable wages.

The tax credit, which is supposed to pay individuals as much as $400 and couples as much as $800, was President Barack Obama's signature tax break in the massive stimulus package enacted in February.

Most workers started receiving the credit through small increases in their paychecks in April.

"While implementing a credit through reduced withholding is an effective way to provide economic stimulus evenly throughout the year, it is difficult to account for everyone's circumstances," said J. Russell George, the Treasury Inspector General for Tax Administration.

"More than 10 percent of all taxpayers who file individual tax returns for 2009 could owe additional taxes because their withholdings were reduced by more than the Making Work Pay Credit.

“If corrective actions are not taken, this problem will continue to plague taxpayers in 2010," George said.