Need a passport? Don't worry during shutdown, State Department says

(CNN) -- For Americans applying for a passport, or citizens of other countries trying to get a visa to the United States, the current government shutdown won't have any effect, the State Department says.

The State Department and the U.S. Agency for International Development are "national security agencies," which means they have national security responsibilities such as representing the United States overseas and representing to Americans what the country's foreign interests are.

Therefore, State Department spokeswoman Jan Psaki told reporters, they will continue working despite the shutdown.

"Regardless of the challenges a shutdown would create, we will continue to operate to advance national interests and protect the health and safety of American citizens and those living abroad," she said at a press briefing Monday.

Long-term effects might differ, but State Department and USAID activities "can be sustained on a limited basis for a short period of time," Psaki explained. She did not define what a "short period" would be.

"Budget wonks," she said, are still crunching the numbers on that.

There is another factor, Psaki said. The fiscal year 2013 appropriations were not received until late March and, as a result, the department will have residual funds available beyond Monday. Some money is available for only one-year funding but most appropriations accounts are multiple-year or fee-based, and are available until the money is spent.

Passports, for example, are fee-based; the cost that Americans pay covers the cost of the document so that service will not be affected.

Some State Department offices are located in federal buildings that could be forced to close in a shutdown, Psaki added, so access would be blocked.