Ultimately, however, agencies will be forced to make choices about where to make cuts. Various departments have already implemented preemptive hiring freezes, and have begun to pinpoint ways to save; they've also identified those areas they say cannot afford to take the hits, and that they'll try to protect from sequestration.

"Under sequestration we're going to keep fully supporting our troops downrange but we're going to see a really pernicious erosion of military readiness of facility readiness and modernization stateside," said Elizabeth Robbins, a spokesperson for the Department of Defense, in an interview with CBSNews.com.

For Robbins' department, that means prioritizing operations and maintenance over research and development, she said, resulting in cutbacks on training not directly related to upcoming missions, the cancellation of some ship and aircraft maintenance in March, and the furlough of nearly 800,000 civilian employees at least one day a week. Robbins argued the furloughs would cause pain not just for the employees - who would be seeing a 20 percent pay cut - but also for the department's operational productivity.

The Federal Aviation Administration (FAA) has also detailed the prospect of furloughs, which representatives say will likely result in the elimination of late-night shifts at around 60 air traffic control towers, and lead towers at 100 small airports to close altogether. The FAA estimates that flights to major cities like New York, Chicago, and San Francisco could be delayed by up to 90 minutes during peak travel hours, which would lead the airlines to preemptively cancel flights.

The Departments of Transportation (DOT) and Homeland Security, as well as the Transportation Security Administration (TSA), and others have warned of similar consequences: Fewer jobs, longer lines.

Most of these changes, however, won't take place until April. Legally, federal employers must notify their employees of a furlough 30 days in advance, which means no furloughs will go into effect until April 1 at the earliest. Moreover, not every agency has identified how it will implement the cuts; the Office of Management and Budget (OMB) plans to release a report on the specifics of agency cuts on March 1, at which point the appropriate actors will have to figure out how to implement. In some cases, working out those details will take time. In the meantime, a group of Republicans has proposed legislation that would give the Obama administration more flexibility in divvying up the cuts - a plan that, if implemented, would ostensibly require yet more decision-making, and more time.

There will, however, be a few immediate effects.

According to an OMB official, as of March 1, the Treasury Department and IRS will have to reduce payments that subsidize clean energy investments, school construction, state and local infrastructure projects, and other priorities.

A number of school districts will also be hit: While the majority of educational funding will not be affected until the 2013-2014 school year, so-called "impact aid" districts - those located on federal property and thus don't have a traditional tax base - will be hit on March 1.