Can I say "budget" instead of "expenses"?
This is a bit tricky. A “budget” doesn’t get paid for, it’s the other way around - it pays for something else. If we consider that a budget is a type of financial plan, then it’s not 100% appropriate in this context. Rather, “costs” would be a better substitute for “expenses” here. Ex: The military budget is paid for through various sources, especially taxes. Ex: The military pays for its costs through paper money.