The U.S. Postal Service, which is a self-funded agency, will remain open, and mail delivery will continue as usual.
Social Security and Medicare benefits will keep coming, but there could be delays in processing new disability applications. Unemployment benefits will still go out.
Most services offered through the Department of Veterans Affairs will continue because lawmakers approve money one year in advance for the VA's health programs. Veterans will still be able to visit hospitals for inpatient care, get mental health counseling at vet centers or get prescriptions filled at VA health clinics. Operators will still staff the crisis hotline, and claims workers will still process payments to cover disability and pension benefits. But those veterans appealing the denial of disability benefits to the Board of Veterans Appeals will have to wait longer for a decision because the board will not issue any decisions during a shutdown.
Federal air traffic controllers remain on the job, and airport screeners will keep funneling passengers through security checkpoints. Federal inspectors continue enforcing safety rules.
Some 5,700 employees at the National Oceanic and Atmospheric Administration will stay on the job because their collection and dissemination of weather and other data are considered necessary "to protect life and property."
All 1.4 million active-duty uniformed military personnel will stay on the job. As for the roughly 800,000 civilian employees, the Pentagon has not determined how many would be classified as essential. All active-duty members are paid on the first and 15th of every month, and they will continue to be paid, thanks to a bill passed by the House and Senate during proceedings Monday. President Barack Obama signed the bill late Monday night.
At MacDill Air Force Base in Tampa, 4,000 civilian employees face furloughs.
The Special Supplemental Nutrition Program for Women, Infants and Children, known as WIC, could shut down. The program provides supplemental food, health care referrals and nutrition education for pregnant women, mothers and their children. School lunches and breakfasts will continue to be served, and food stamps, known as the Supplemental Nutrition Assistance Program, or SNAP, will continue to be distributed. But several smaller feeding programs will not have the money to operate.
Americans still have to pay their taxes and file federal tax returns, but the Internal Revenue Service says it will suspend all audits. Got questions? Sorry, the IRS says taxpayer services, including toll-free help lines, will be shut down as well.
Many low-to-moderate income borrowers and first-time home buyers seeking government-backed mortgages will face delays during the shutdown. The Federal Housing Administration, which guarantees about 30 percent of home mortgages, won't underwrite or approve any new loans during the shutdown. Action on government-backed loans to small businesses will be suspended.
Federal courts could continue to operate for about two weeks with reserve funds. After reserve funds are depleted, only essential employees would continue to work. Each court will have flexibility in determining which employees are essential other than judges, who will work.
Don't expect a shutdown to bring any relief if you're breaking federal law or facing federal charges. Essential staff at the U.S. Attorney's Office will remain on duty. And the courts stay open.
"If the shutdown lasts more than 10 business days, there may be a delay in payments to employees and jurors, but we will all continue to do our jobs," said U.S. District Judge Anne C. Conway, chief judge for the Middle District of Florida.
The department will still distribute $22 billion to public schools that is normally obligated on Oct. 1. Pell Grants and Federal Direct Student Loans will continue to be processed, although payments may slow if there are fewer employees to process them. Other grant programs that use dollars that have previously been appropriated will continue, including Race to the Top, Investing in Innovation and Promise Neighborhoods.
All national parks will be closed, as will the Smithsonian museums, including the National Zoo in Washington. The Statue of Liberty in New York, the loop road at Acadia National Park in Maine, Skyline Drive in Virginia, and Philadelphia's Independence National Historical Park, home of Independence Hall and the Liberty Bell, will be off limits. Visitors using overnight campgrounds or other park facilities will be given 48 hours to make alternate arrangements and leave the park.
Information from the Washington Post and Associated Press was included in this report.