Budget
Historically, most budgets are created based on prior year costs plus cost-of-living increases. There is also a zero-based budget process where you start at zero and budget categories based on need for each dollar rather than an automatic cost-of-living increase.
You have essential and non-essential departments and should budget accordingly.
There is no good reason that the government should ever have to be shut down. If that does occur, then all those in the Senate, Congress, and the Executive branch should also receive no pay. Each is paid by the taxes of American citizens and has a job to do…one of which is to keep the government running, along with following the Constitution and keeping us safe.