Some things you can't plan for. There's a good chance that at some point, you'll incur a hefty bill you couldn't possibly have foreseen. You should save a contingency budget to ensure a minor upset doesn't become a major financial crisis. This guide explains why it always pays to save for a rainy day.
What kinds of eventualities do I have to save and plan for?
Particulars will vary from business to business. You could have problems with suppliers, with cash flow, with your building or your equipment. Or you could be hit with a bill you just didn't anticipate. Disaster could also strike in the form of fire or flood or a pandemic. No matter what happens, you need to have at least three months' worth of survival funds ready to go.
Business continuity planning: the process of determining and planning for how a business will survive if disaster strikes