WASHINGTON - Filing tax returns electronically is usually a simple matter, but certain data entry errors or inconsistencies can cause the IRS to reject an e-filed return.

According to H&R Block, rejections most commonly occur because of incorrect entries for a taxpayer's adjusted gross income, date of birth or Social Security number for the taxpayer, spouse or children.

Most tax preparation software will not e-file a return in which it detects a major problem or error. The program may also reject returns with Social Security numbers not in the range of known numbers it has from the government.

To prepare and file a tax return electronically, you need:

-A copy of last year's tax return.

-Social Security numbers for yourself, spouse and dependents.

-W-2 forms from all employers for yourself and spouse.

-1099 forms showing interest, dividends, retirement or other income paid to you during the year, including refunds, credits and state and local taxes.

-Income receipts from rental real estate, royalties, partnerships, S corporations and trusts.

-Receipts and records for other income or expenses such as rental real estate, partnerships, trusts and Social Security benefits.

-Receipts pertaining to your small business.

-Unemployment compensation records.

Those who itemize deductions on Schedule A may also need the following:

-Receipts for medical and dental expenses.

-Receipts from state and local taxes, real estate taxes, personal property taxes.

-Form 1098 for home mortgage interest and points.

-Receipts for charitable contributions and gifts.

-Casualty and theft losses.

-Job expenses.

Taxpayers due a refund should have bank account and routing numbers for direct deposit of refunds.

Those owing tax can pay electronically by charging it to a credit card, having it withdrawn from a bank account or enrolling in the U.S. Treasury's Electronic Federal Tax Payment System. See http://eftps.gov or the IRS Web site at http://www.irs.gov for more information.

Tax preparation programs like TurboTax or TaxCut can e-file a return, as can online tax preparers and tax professionals. The IRS can also find an e-filer for you if you enter your ZIP code in the e-file locator box on the IRS Web site.

The return is transmitted via a modem to an electronic return transmitter, which converts the file to a format that meets IRS specifications and forwards it to the IRS for processing. Within 48 hours the IRS confirms whether the return has been accepted or rejected.

Taxpayers who file electronically create a personal identification number, which serves as their electronic signature and requires knowing their 2004 adjusted gross income. Taxpayers who don't create a PIN can still file electronically but will also have to mail Form 8453-OL to the appropriate IRS service center after they have received IRS confirmation that the e-filed return was accepted.

On the Net:

IRS: http://www.irs.gov

Essential facts for the 2006 tax-filing season:

FILING DEADLINE: April 17, 2006 (because April 15 falls on a Saturday). In Maine, Maryland, Massachusetts, New Hampshire, New York, Vermont and the District of Columbia, the deadline is April 18, because of the Patriot's Day holiday in Massachusetts, where the IRS has a processing facility.

FILING EXTENSION: automatic six-month extension to Oct. 16, as long as Form 4868 is filed by April 17.

WHAT'S NEW: stricter rules for donating vehicles to charity; tax breaks for hurricane victims and those who helped them; higher mileage rate for business use of vehicles; higher ceilings for IRAs and other retirement savings plans; new definition and tests for "qualifying child"; new online IRS tools for determining qualification for alternative minimum tax and earned income tax credit; inflation adjustment for various other tax credits, deductions and categories.

IRS FORMS: Download at http://www.irs.gov by navigating to "Forms and Publications"; order by mail by calling 1-800-829-3676.

ONLINE TAX HELP: http://www.irs.gov

PHONE TAX HELP: 1-800-829-1040 for individuals, 1-800-829-4059 (TDD) for those with hearing impairment, 1-800-829-4933 for businesses, 1-866-562-5227 for hurricane victims.