New tax breaks enacted last year are causing confusion for taxpayers and enforcement problems for the Internal Revenue Service, according to a government report issued Thursday, the deadline for filing individual returns.

As of March 5, the IRS erroneously gave out $24.2 million in Making Work Pay tax credits, according to the report by J. Russell George, the Treasury inspector general for tax administration. The IRS issued a total of $25 billion worth of the credits during the period, for an error rate of less than one-tenth of 1 percent.

The IRS also erroneously issued about $4.7 million in tax credits meant for people who bought plug-in electric cars. The new tax breaks were enacted as part of the massive economic recovery package passed last year.

"Our report concludes that the IRS is having a mixed filing season this year," George said. "On the one hand, they are having difficulty implementing many of the changes created by the passage of the laws designed to stimulate the economy. On the other hand, the news is not all bad as the IRS is detecting and stopping more erroneous refunds this year."

The report covers returns processed as of March 5. At the time, the IRS had received about 61 million returns. The agency expects to receive about 140 million individual returns this year.

"Any time you have major tax changes you will see some confusion over it," said IRS spokesman Terry Lemons. The IRS is doing "everything we can" to work through problems and process returns quickly.

The stimulus package enacted last year presented many challenges for taxpayers and the IRS, making an already complicated tax system even more complex. There were tax credits for qualified families who buy new homes or make energy improvements to existing ones, as well as tax breaks to help pay college tuition or buy new cars.

The Making Work Pay tax credit was President Barack Obama's signature tax break in the package. It provides individuals with up to $400 and couples up to $800.

The homebuyer tax credit was so popular that Congress extended and expanded it in November. Buyers who have owned their current homes at least five years are eligible, subject to income limits, for tax credits of up to $6,500. First-time homebuyers — or people who haven't owned homes in the previous three years — can get up to $8,000. To qualify, buyers have to sign purchase agreements before May 1 and close before July 1.

The IRS expects half the people claiming the homebuyer credit not to include proper documentation, such as a settlement statement, and that will delay refunds, according to the report.

As of April 2, the average refund was $2,950, up about $255 over last year, Lemons said. The fastest way to get a refund: file electronically and have the refund deposited directly into a bank account, which takes about 10 days.

Refunds can take six to eight weeks for last-minute filers who use paper returns and receive checks, Lemons said.