NEW YORK (CNN/Money) - The Internal Revenue Service announced Tuesday that it is offering tax cheats a single opportunity to come forward and pay up without having to face stiff penalties.

The effort, which is part of a 30-month strategy to prevent tax shelters, would offer a limited opportunity for offending individuals and companies to come forward and pay up without fear of facing the full penalty.

"People entered into these deals often at the behest of lawyers and accountants peddling flaky tax products," IRS Commissioner Mark W. Everson said in a prepared statement. "We're offering taxpayers a quick, quiet and cost-effective way to put these deals behind them."

If they come forward, individuals and companies involved would have to pay the full amount of taxes owed as well as interest, and either a quarter or half of the penalty the IRS would typically assess.

The IRS estimates that more than 4,000 taxpayers have been involved in these different transactions, which include small business owners, large corporations and wealthy individuals.

The IRS said that individuals who want to settle up on owed taxes have until January 23, 2006 to submit their papers.

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