The bare minimum depends on the company. I've worked at a place where other people were responsible for program design, and I had to translate detailed specs into COBOL. That's really not much fun, but I didn't need to know anything about the business at first.
Once you start having some say in program design (or, preferably, if you start there), you need to know what the business is doing, so you can understand what your users actually need. Knowing more about the business means that people need to tell you things in less detail, so your value to the business grows. You can sometimes do things on your own initiative that help the business, also increasing your value. This is often reflected in your job title and paycheck.
It's also helpful to have some idea of where the money comes from, where it goes, and why some of it goes into your pocket. You really should have some sort of idea why the company pays you. It may help your motivation to learn to know that those new contracts are the things that provide your pay.
It's also likely to help if you know what business affairs mean to you, how a new contract affects you.
Obviously, if you don't want to stay in a purely technical role forever (and, empirically, that seems a little rare), you will need to understand the business much better, but it will help anybody to understand what's going on.