Contingency plans focus on which agencies will close, which employees will have to show up for work and who gets paid, CNN Money reported Friday.
A prime factor in the decision is an agency's determination of what programs and services are essential. Programs considered "non-essential" will be closed and their staff furloughed.
Closing are federal museums such as the Smithsonian, as well as the National Zoo.
Processing of federally underwritten home loans will be delayed because most employees of the Federal Housing Administration will be sent home.
The Food and Drug Administration will maintain operations related to recalls and the Centers for Disease Control and Prevention will maintain a minimal staff for outbreak investigations and the emergency operations center.
Members of the armed forces will still put their lives on the line, but their paychecks may be delayed if the shutdown goes past Oct. 7. Temporary duty travel will be canceled, unless it's related to the conflict in Afghanistan or the protection of essential facilities such as embassies.
Civilian defense employees engaged in essential activities will keep working.
Federal courts will operate, although judges will reassess their ability to work about mid-October.
Astronauts in the International Space Station will still have a ground crew, but just about everything else at NASA will be shuttered.
Presidential appointees will stay on the job. People whose jobs are funded by appropriations other than those included in the contested budget will still show up for work.