The Internal Revenue Service said Monday that its systems are operational for all remaining individual and business tax returns.

In an email Monday to tax software developers and tax returns transmitters, the IRS said it had completed its controlled launch of the remaining individual and business tax returns on Sunday, March 3, 2013. The IRS had said in an earlier email last Wednesday that it planned to allow the forms that have not been available for electronic filing yet this tax season to go through during the first week of March (see IRS Plans to Enable Remaining Tax Forms to be Filed).

The IRS said Monday that its Modernized e-File System, or MeF, is operational and all individual and business tax returns can now be processed.

“You can enable all your products, including online filing, and begin submitting returns, it said. “As we have communicated throughout the filing season, we appreciate your continued partnership and support to ensure a successful startup.”

Remaining Tax Forms Now Being Processed:

•    Form 3800 General Business Credit
•    Form 4136 Credit for Federal Tax Paid on Fuels
•    Form 5074 Allocation of Individual Income Tax to Guam or the Commonwealth of the Northern Mariana Islands
•    Form 5471 Information Return of U.S. Persons With Respect to Certain Foreign Corporations
•    Form 5695 Residential Energy Credits
•    Form 5735 American Samoa Economic Development Credit  
•    Form 5884 Work Opportunity Credit
•    Form 6478 Credit for Alcohol Used as Fuel
•    Form 6765 Credit for Increasing Research Activities
•    Form 8396 Mortgage Interest Credit
•    Form 8582 Passive Activity Loss Limitations
•    Form 8820 Orphan Drug Credit
•    Form 8834 Qualified Plug-in Electric and Electric Vehicle Credit
•    Form 8844 Empowerment Zone and Renewal Community Employment Credit
•    Form 8845 Indian Employment Credit
•    Form 8859 District of Columbia First-Time Homebuyer Credit
•    Form 8864 Biodiesel and Renewable Diesel Fuels Credit
•    Form 8874 New Markets Credits
•    Form 8900 Qualified Railroad Track Maintenance Credit
•    Form 8903 Domestic Production Activities Deduction
•    Form 8908 Energy Efficient Home Credit
•    Form 8909 Energy Efficient Appliance Credit
•    Form 8910 Alternative Motor Vehicle Credit
•    Form 8911 Alternative Fuel Vehicle Refueling Property Credit
•    Form 8912 Credit to Holders of Tax Credit Bonds
•    Form 8923 Mine Rescue Team Training Credit
•    Form 8932 Credit for Employer Differential Wage Payments

•    Form 8936 Qualified Plug-in Electric Drive Motor Vehicle Credit

The IRS also announced Monday that over the weekend, it completed reprogramming and testing of its systems for tax-year 2012, including all remaining updates required by the American Taxpayer Relief Act, which was enacted by Congress in January. This final step clears the way for those claiming residential energy credits on Form 5695 and various business tax credits and deductions to file their returns.

The IRS began accepting 2012 returns in phases as it worked to update various forms and instructions and made critical adjustments to its processing systems to reflect the current law. As a result, the agency began accepting most returns filed by individual taxpayers on Jan. 30. Additional returns could be accepted in February. All the remaining returns, affecting in relative terms the smallest group of taxpayers, can now be filed.

Despite the long delays, the IRS so far has not announced any extension to tax season. With just six weeks to go before this year’s April 15 deadline, the IRS is instead reminding taxpayers that the best way to file an accurate return is to e-file, choose direct deposit if expecting a refund and take advantage of the wide variety of tax-filing and tax-help resources available on IRS.gov.

In addition, the IRS reminded people who need more time to finish their returns that they can get an automatic six-month tax-filing extension by going to the Free File link or filing Form 4868.