What to Know
More than 800,000 federal employees would be affected by a partial government shutdown.
However, federal workers including those in law enforcement, corrections, Homeland Security, TSA and other agencies would stay on the job.
Federal checks will still go out, and passports will still be issued, But applying for the first time for federal programs may take longer.
If the federal government shuts down, can you get that passport renewed for your January trip? What about your Social Security check? And do you have to file your taxes?
We have answers.
Q: What's open and what's closed?
A: Social Security checks will go out and troops will remain at their posts. Doctors and hospitals will receive their Medicare and Medicaid reimbursements. The U.S. Postal Service, busy delivering packages for the holiday season, is an independent agency and won't be affected. Passport services, which are funded by fees and not government spending, will also continue.
Virtually every essential government agency, including the FBI, the Border Patrol and the Coast Guard, will remain open. Transportation Security Administration officers will staff airport checkpoints.
The air traffic control system, food inspection, Medicare, veterans' health care and many other essential government programs will run as usual. The Federal Emergency Management Agency can continue to respond to disasters.
Nearly 90 percent of the Department of Homeland Security's 240,000 employees will be at work because they're considered essential.
Special counsel Robert Mueller's office, which is investigating potential ties between the Trump campaign and Russia, is unaffected by a shutdown.
But hundreds of thousands of federal workers will be forced off the job, and some services will go dark.
In the past, the vast majority of national parks were closed to visitors and campers, but beginning with the last government shutdown, in January, the Interior Department has tried to make parks as accessible as possible despite bare-bones staffing levels. Some are staying open thanks to funding from states and charitable groups.
Q: How many government workers could see their paychecks delayed?
A: More than 800,000 federal employees would see their jobs disrupted, including more than half who would be forced to continue working without pay, the AP reported.
According to a report by Democrats on the Senate Appropriations Committee, more than 420,000 federal employees deemed essential would continue to work without pay during a partial shutdown. That includes employees working in law enforcement, corrections, Homeland Security, TSA, Customs and Border Protection agents and 42,000 Coast Guard employees.
But more than 380,000 employees will be furloughed.
All employees should be paid back in full once the government reopens.
Q: What about federal contractors?
A: Government contractors are in an even tougher situation. If their contract is funded, they are likely to be OK -- but in past shutdowns, some furloughed agencies have issued stop-work orders to contractors, according to the National Law Review.
Contractors may not be made whole after a shutdown. And remember, not all contractors are big-money corporations -- the janitors at many government buildings are also contractors.
Q: I ordered my holiday presents from Amazon! Will they get here?
A: The U.S. Postal Service wouldn't be affected by any government shutdown because it's an independent agency and has its own sources of revenue. FedEx and UPS are private companies and would not be affected.
Q: I rely on my income from Social Security. Will my check still arrive?
A: Social Security checks will still go out. So will payments to Medicaid and Medicare programs and for veterans' programs, including the GI Bill and VA hospitals. But if you are applying to join one of those programs, you might have to wait.
And the U.S. food stamp program has only limited funding.
Q: What about the Mueller investigation?
A: It is funded "from a permanent indefinite appropriation and would be unaffected in the event of a shutdown," a Justice Department spokesperson told CNN.
Q: Can I go see Independence Hall in Philadelphia, the Smithsonian's National Zoo in Washington, D.C. and other national parks?
A: That depends. Most national historic sites, including Independence National Historic Park, have areas funded by the National Park Service and other areas funded by private organizations. Some Park Service-funded locations would probably close.
In the past, the vast majority of national parks were closed to visitors and campers, but during the last government shutdown in January the Interior Department tried to make parks as accessible as possible despite bare-bones staffing levels.
Q: Can I renew my passport?
A: The State Department will keep issuing passports, Bloomberg reported. But you might have a little trouble accessing their offices if the passport office you want to go to is inside a building run by another agency and that agency gets shut down.
Q: Do I have to pay my taxes?
However, the IRS would have to furlough parts of its staff, which could affect the number of people available for tax prep help or investigations.
Q: Can my kids still track Santa?
A: Yes. NORAD said that even if the government shuts down it will continue with its 63-year tradition of NORAD Tracks Santa in collaboration with more than 1,500 volunteers.