Government Shutdown: Which Offices Will Stay Open, Which Will Close

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As Democrats and Republicans bicker over $30 billion, thousands of government employees fret over whether they can go to work on Monday. After the current continuing budget resolution expires at 12:01 a.m. Friday, all "nonessential" government employees will be sent home until Congress passes and the president signs a budget for the remainder of fiscal year 2011.

The problem is, no one knows exactly who is considered "essential." A senior administration official said about 800,000 federal employees would be prevented from working in the event of a shutdown. These furloughed workers would not be paid during the shutdown, zapping $1.1 billion out of the economy in unpaid wages for a week-long shutdown.

ABC News has rounded up information from as many agencies as possible to find out who stays home who goes to work, and how it might affect you.

Military: Working Military personnel will continue to work but will not be paid during a shutdown. They should earn backpay once Congress passes an appropriations bill. A bipartisan group of senators introduced a bill today to make sure members of the military would get paid even if the government shut down.

Postal Service: Working The government shutdown won't affect mail delivery or mail processing, as the Postal Service is self-funded. "We don't get any taxpayer money. So we are not part of appropriations process. We will carry on and do what we always do: Deliver the mail," said a Postal Service spokesperson.

Medicare: Working People will still receive Medicare benefits, paid for by an emergency trust fund. If, hypothetically, the shutdown were to last for many months, Medicare benefits would stop, but the odds of a shutdown that lengthy are slim.

Social Security: Working Payments will continue as usual.

IRS: Working, but Limited Services The tax deadline, April 18, will not change, but the IRS will not process any paper tax returns, which account for 30 percent of the total returns filed. Tax audits will be suspended, and trademark and patent applications could also be delayed. The IRS will, however, continue to collect tax money.

Department of Veterans Affairs: Working but Limited Services Veterans health services, benefits payments and cemetary services will not be affected because they are appropriated on a two-year cycle. Answers to e-mail and telephone inquiries, hiring, recruiting, training and fraud investigations will be suspended.

Airports: Working Air traffic controllers and Transportation Security Administration agents are considered "essential" employees.

Congress: Working Every member of Congress decides who on their staff is "essential" personnel. Many have said they will not furlough any of their staff members. Reps. Darrell Isa, R-Calif.; Dennis Cardoza, D-Calif.; and Ander Crenshaw, R-Fla.; all told Roll Call they would maintain their full staff in the event of a shutdown. Any staff members who are furloughed will not only be banned from the halls of Congress during the shutdown period, they will also have to turn off their office-issued BlackBerry cell phones.

Department of Homeland Security: Working But Limited Services Over 80% of the DHS workforce has been deemed to be "essential" personnel for agencies such as TSA, Customs and Border Protection, Secret Service, Coast Guard, FEMA and Immigration Customs Enforcement. The host of employees from intelligence analysts to cyber security officials are also considered "essential" and will continue working.

Law Enforcement: Working At such agencies as the FBI, Drug Enforcement Administration, Marshals, and Bureau of Alcohol, Tobacco, Firearms and Explosives it will, for the most part, be business as usual.

Department of Justice: Working but Limited Services The Criminal Division and the National Security Division, which conducts counterterrorism/counterespionage operations and wiretaps, would continue working, but large bureaucratic agencies, such as the Office of Justice Programs and Bureau of Justice Statistics, are not likely to be viewed as essential.

Federal Prisons: Working The prison system will be virtually unaffected by a government shutdown.

Passport Processing: Not Working Passport processing employees will be sent home during the shutdown, causing delays in the 200,000 passport applications currently pending. Visa processing will aslo be delayed or halted.

Federal Housing Administration: Not Working In the event of a shutdown, the FHA, which guarantees 30 percent of all mortgages, would not be able to guarantee housing loans. That "would have significant impact on the housing market," according to a senior administration official.

National Transportation Safety Board: Working but Limited The chairman and the managing director may authorize very specific investigative activity, such as new investigations on major accidents involving significant casualties; accidents in which investigation is deemed necessary to transportation safety; and extremely limited support for ongoing investigative activity in which delay could pose a risk to public safety. All other activities will cease.

Small Business Administration: Not Working SBA approval of business loan guarantees and direct loans to people would stop, which would have an "impact on economic momentum," according to a senior administration official.

State Department: Working but Limited The department will continue working domestically, issuing travel advisories and working with American citizens. It refused to comment on all foreign services.Other consular functions, like helping Americans in distress abroad, are likely to continue and other functions of the State Dept and parts of its embassies that are deemed essential for national security reasons will continue.

Environmental Protection Agency: Working but Limited The EPA will continue to do work that "affects safety and life" including monitoring radiation from Japan. Environmental claims processing would cease, along with toxic waste clean-up at EPA Superfund sites.The EPA will cease issuing permits, and delay work on environmental impact statements. And urgent new initiatives, including efforts to address mercury in the air and unregulated contaminants in drinking water, would be set back.

Department of Energy: Working The Energy Department will not furlough any employees and it will be basically business as usual becausee of a "no-year fund" that would pay for expenses in the event of a lapse in federal funding, according to a department official.

National Park Service: Not Working All national parks, such as Yosemite, Mount Rushmore, the Grand Canyon and monuments, would be closed. A Department of the Interior spokesperson said, "the National Park Service, Fish and Wildlife Service and Bureau of Land Management will close and secure park, refuge and visitor facilities on public lands. Limited personnel needed to protect life and property on public lands, such as law enforcement, emergency services and firefighting personnel, will be exempted from furlough." During the 1995 shutdown, the National Park Service turned away roughly 7 million visitors 2 million visitors were lock out of national monuments and museums.. The gates to major parks were closed and locked up, and wire fences and chains were strung up around national monuments. This also means D.C's Cherry Blossom Festival events that take place on federal park property, most notably Saturday's parade, will be canceled.

Department of Defense: Working but Limited A "significant number" of civilian employees will be furloughed.

Smithsonian Institute: Not Working All Smithsonian museums will be closed.

National Institutes of Health: Working but Limited NIH will not take any new patients or start new trials, but the clinical trials in progress will continue. There are seven new procedures that are scheduled to begin next week. Of those seve, four involve children and two involve children with cancer. There are 640 current clinical trials, none of which will be able to accept new patients during a shutdown.

Census Bureau: Not Working The Census Bureau, as well as the Bureau of Economic Analysis and the Economics and Statistics Administration, among others, would be closed. That means economic indicators scheduled for release will not be available, according to an administration official.

ABC News' Kristina Bergess, Nick Gass, Z. Byron Wolf, Jake Tapper, Luis Martinez, Huma Khan, Kirit Radia and Jim Sciutto contributed to this report.