"Eighty percent of U.S. taxpayers use a tax preparer or tax preparation software," said IRS Commissioner Doug Shulman in a national conference call, calling the proposed regulation of the tax preparation industry "a monumental shift" in IRS policy.

The IRS will require all paid tax return preparers to register -- for a fee -- and obtain a preparer tax identification number, said Shulman.

The IRS will establish competency testing for all paid tax return preparers required to register with the IRS who are not attorneys, certified public accountants or enrolled agents, he said.

In addition, the IRS will require 15 hours of annual continuing education for tax return preparers, said Shulman, noting that most preparers provide excellent service to the American public.

But since the nation's tax code has grown increasingly complex, the tax return preparation industry has grown into a multibillion-dollar industry, he said.

What's also grown has been the opportunity for tax preparers to make mistakes. A recent Government Accounting Office study of commercial tax return preparation firms noted that only two of the 19 tax return preparers had the correct tax liability and refund amounts on returns they prepared.

Shulman said taxpayers should consider whether the individual or firm they hire to prepare their tax return will be around to answer questions on a return.

The public should also be cautious of tax preparers who claim they can obtain larger refunds than others, he said.

"Taxpayers should avoid preparers who base their fee on a percentage of the refund," he added.

The IRS also plans to assemble a task force to establish industry standards for tax preparation software, said Shulman.

As a first step in increasing scrutiny of firms that prepare tax returns, Shulman said the IRS was sending letters about possible visits from the agency to 10,000 of the large tax preparers across the country.

"Some of the IRS visits will be announced and some will not be announced. In some cases, an IRS agent will pose as a taxpayer to see what kind of service is being offered," said Shulman, who also offered suggestions to consumers facing the traditional April 15 deadline for filing their 2009 tax return.

Information on opportunities for tax saving -- from the "making work pay" credit to energy improvements -- is available at irs.gov, he said. Shulman noted that the electronic filing of tax returns and setting up direct deposit of returns into a taxpayer's bank account was the most expedient way to receive an IRS refund.